Precalculus Examples

Find the Roots (Zeros) x^5-x^4-5x^3+x^2+8x+4
Step 1
Set equal to .
Step 2
Solve for .
Tap for more steps...
Step 2.1
Factor the left side of the equation.
Tap for more steps...
Step 2.1.1
Regroup terms.
Step 2.1.2
Factor out of .
Tap for more steps...
Step 2.1.2.1
Factor out of .
Step 2.1.2.2
Multiply by .
Step 2.1.2.3
Factor out of .
Step 2.1.3
Rewrite as .
Step 2.1.4
Since both terms are perfect cubes, factor using the sum of cubes formula, where and .
Step 2.1.5
Factor.
Tap for more steps...
Step 2.1.5.1
Simplify.
Tap for more steps...
Step 2.1.5.1.1
Multiply by .
Step 2.1.5.1.2
One to any power is one.
Step 2.1.5.2
Remove unnecessary parentheses.
Step 2.1.6
Factor using the rational roots test.
Tap for more steps...
Step 2.1.6.1
If a polynomial function has integer coefficients, then every rational zero will have the form where is a factor of the constant and is a factor of the leading coefficient.
Step 2.1.6.2
Find every combination of . These are the possible roots of the polynomial function.
Step 2.1.6.3
Substitute and simplify the expression. In this case, the expression is equal to so is a root of the polynomial.
Tap for more steps...
Step 2.1.6.3.1
Substitute into the polynomial.
Step 2.1.6.3.2
Raise to the power of .
Step 2.1.6.3.3
Multiply by .
Step 2.1.6.3.4
Raise to the power of .
Step 2.1.6.3.5
Multiply by .
Step 2.1.6.3.6
Add and .
Step 2.1.6.3.7
Multiply by .
Step 2.1.6.3.8
Subtract from .
Step 2.1.6.3.9
Add and .
Step 2.1.6.4
Since is a known root, divide the polynomial by to find the quotient polynomial. This polynomial can then be used to find the remaining roots.
Step 2.1.6.5
Divide by .
Tap for more steps...
Step 2.1.6.5.1
Set up the polynomials to be divided. If there is not a term for every exponent, insert one with a value of .
+--+++
Step 2.1.6.5.2
Divide the highest order term in the dividend by the highest order term in divisor .
-
+--+++
Step 2.1.6.5.3
Multiply the new quotient term by the divisor.
-
+--+++
--
Step 2.1.6.5.4
The expression needs to be subtracted from the dividend, so change all the signs in
-
+--+++
++
Step 2.1.6.5.5
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
-
+--+++
++
-
Step 2.1.6.5.6
Pull the next terms from the original dividend down into the current dividend.
-
+--+++
++
-+
Step 2.1.6.5.7
Divide the highest order term in the dividend by the highest order term in divisor .
--
+--+++
++
-+
Step 2.1.6.5.8
Multiply the new quotient term by the divisor.
--
+--+++
++
-+
--
Step 2.1.6.5.9
The expression needs to be subtracted from the dividend, so change all the signs in
--
+--+++
++
-+
++
Step 2.1.6.5.10
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
--
+--+++
++
-+
++
+
Step 2.1.6.5.11
Pull the next terms from the original dividend down into the current dividend.
--
+--+++
++
-+
++
++
Step 2.1.6.5.12
Divide the highest order term in the dividend by the highest order term in divisor .
--+
+--+++
++
-+
++
++
Step 2.1.6.5.13
Multiply the new quotient term by the divisor.
--+
+--+++
++
-+
++
++
++
Step 2.1.6.5.14
The expression needs to be subtracted from the dividend, so change all the signs in
--+
+--+++
++
-+
++
++
--
Step 2.1.6.5.15
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
--+
+--+++
++
-+
++
++
--
+
Step 2.1.6.5.16
Pull the next terms from the original dividend down into the current dividend.
--+
+--+++
++
-+
++
++
--
++
Step 2.1.6.5.17
Divide the highest order term in the dividend by the highest order term in divisor .
--++
+--+++
++
-+
++
++
--
++
Step 2.1.6.5.18
Multiply the new quotient term by the divisor.
--++
+--+++
++
-+
++
++
--
++
++
Step 2.1.6.5.19
The expression needs to be subtracted from the dividend, so change all the signs in
--++
+--+++
++
-+
++
++
--
++
--
Step 2.1.6.5.20
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
--++
+--+++
++
-+
++
++
--
++
--
Step 2.1.6.5.21
Since the remander is , the final answer is the quotient.
Step 2.1.6.6
Write as a set of factors.
Step 2.1.7
Factor out of .
Tap for more steps...
Step 2.1.7.1
Factor out of .
Step 2.1.7.2
Factor out of .
Step 2.1.8
Apply the distributive property.
Step 2.1.9
Simplify.
Tap for more steps...
Step 2.1.9.1
Multiply by by adding the exponents.
Tap for more steps...
Step 2.1.9.1.1
Use the power rule to combine exponents.
Step 2.1.9.1.2
Add and .
Step 2.1.9.2
Rewrite using the commutative property of multiplication.
Step 2.1.9.3
Multiply by .
Step 2.1.10
Multiply by by adding the exponents.
Tap for more steps...
Step 2.1.10.1
Move .
Step 2.1.10.2
Multiply by .
Tap for more steps...
Step 2.1.10.2.1
Raise to the power of .
Step 2.1.10.2.2
Use the power rule to combine exponents.
Step 2.1.10.3
Add and .
Step 2.1.11
Subtract from .
Step 2.1.12
Subtract from .
Step 2.2
If any individual factor on the left side of the equation is equal to , the entire expression will be equal to .
Step 2.3
Set equal to and solve for .
Tap for more steps...
Step 2.3.1
Set equal to .
Step 2.3.2
Subtract from both sides of the equation.
Step 2.4
Set equal to and solve for .
Tap for more steps...
Step 2.4.1
Set equal to .
Step 2.4.2
Solve for .
Tap for more steps...
Step 2.4.2.1
Factor the left side of the equation.
Tap for more steps...
Step 2.4.2.1.1
Regroup terms.
Step 2.4.2.1.2
Factor out of .
Tap for more steps...
Step 2.4.2.1.2.1
Factor out of .
Step 2.4.2.1.2.2
Factor out of .
Step 2.4.2.1.2.3
Factor out of .
Step 2.4.2.1.3
Factor by grouping.
Tap for more steps...
Step 2.4.2.1.3.1
For a polynomial of the form , rewrite the middle term as a sum of two terms whose product is and whose sum is .
Tap for more steps...
Step 2.4.2.1.3.1.1
Factor out of .
Step 2.4.2.1.3.1.2
Rewrite as plus
Step 2.4.2.1.3.1.3
Apply the distributive property.
Step 2.4.2.1.3.2
Factor out the greatest common factor from each group.
Tap for more steps...
Step 2.4.2.1.3.2.1
Group the first two terms and the last two terms.
Step 2.4.2.1.3.2.2
Factor out the greatest common factor (GCF) from each group.
Step 2.4.2.1.3.3
Factor the polynomial by factoring out the greatest common factor, .
Step 2.4.2.1.4
Factor out of .
Tap for more steps...
Step 2.4.2.1.4.1
Factor out of .
Step 2.4.2.1.4.2
Factor out of .
Step 2.4.2.1.4.3
Factor out of .
Step 2.4.2.1.5
Factor.
Tap for more steps...
Step 2.4.2.1.5.1
Rewrite in a factored form.
Tap for more steps...
Step 2.4.2.1.5.1.1
Factor using the rational roots test.
Tap for more steps...
Step 2.4.2.1.5.1.1.1
If a polynomial function has integer coefficients, then every rational zero will have the form where is a factor of the constant and is a factor of the leading coefficient.
Step 2.4.2.1.5.1.1.2
Find every combination of . These are the possible roots of the polynomial function.
Step 2.4.2.1.5.1.1.3
Substitute and simplify the expression. In this case, the expression is equal to so is a root of the polynomial.
Tap for more steps...
Step 2.4.2.1.5.1.1.3.1
Substitute into the polynomial.
Step 2.4.2.1.5.1.1.3.2
Raise to the power of .
Step 2.4.2.1.5.1.1.3.3
Multiply by .
Step 2.4.2.1.5.1.1.3.4
Add and .
Step 2.4.2.1.5.1.1.3.5
Subtract from .
Step 2.4.2.1.5.1.1.4
Since is a known root, divide the polynomial by to find the quotient polynomial. This polynomial can then be used to find the remaining roots.
Step 2.4.2.1.5.1.1.5
Divide by .
Tap for more steps...
Step 2.4.2.1.5.1.1.5.1
Set up the polynomials to be divided. If there is not a term for every exponent, insert one with a value of .
++--
Step 2.4.2.1.5.1.1.5.2
Divide the highest order term in the dividend by the highest order term in divisor .
++--
Step 2.4.2.1.5.1.1.5.3
Multiply the new quotient term by the divisor.
++--
++
Step 2.4.2.1.5.1.1.5.4
The expression needs to be subtracted from the dividend, so change all the signs in
++--
--
Step 2.4.2.1.5.1.1.5.5
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
++--
--
-
Step 2.4.2.1.5.1.1.5.6
Pull the next terms from the original dividend down into the current dividend.
++--
--
--
Step 2.4.2.1.5.1.1.5.7
Divide the highest order term in the dividend by the highest order term in divisor .
-
++--
--
--
Step 2.4.2.1.5.1.1.5.8
Multiply the new quotient term by the divisor.
-
++--
--
--
--
Step 2.4.2.1.5.1.1.5.9
The expression needs to be subtracted from the dividend, so change all the signs in
-
++--
--
--
++
Step 2.4.2.1.5.1.1.5.10
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
-
++--
--
--
++
-
Step 2.4.2.1.5.1.1.5.11
Pull the next terms from the original dividend down into the current dividend.
-
++--
--
--
++
--
Step 2.4.2.1.5.1.1.5.12
Divide the highest order term in the dividend by the highest order term in divisor .
--
++--
--
--
++
--
Step 2.4.2.1.5.1.1.5.13
Multiply the new quotient term by the divisor.
--
++--
--
--
++
--
--
Step 2.4.2.1.5.1.1.5.14
The expression needs to be subtracted from the dividend, so change all the signs in
--
++--
--
--
++
--
++
Step 2.4.2.1.5.1.1.5.15
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
--
++--
--
--
++
--
++
Step 2.4.2.1.5.1.1.5.16
Since the remander is , the final answer is the quotient.
Step 2.4.2.1.5.1.1.6
Write as a set of factors.
Step 2.4.2.1.5.1.2
Factor using the AC method.
Tap for more steps...
Step 2.4.2.1.5.1.2.1
Factor using the AC method.
Tap for more steps...
Step 2.4.2.1.5.1.2.1.1
Consider the form . Find a pair of integers whose product is and whose sum is . In this case, whose product is and whose sum is .
Step 2.4.2.1.5.1.2.1.2
Write the factored form using these integers.
Step 2.4.2.1.5.1.2.2
Remove unnecessary parentheses.
Step 2.4.2.1.5.2
Remove unnecessary parentheses.
Step 2.4.2.1.6
Combine exponents.
Tap for more steps...
Step 2.4.2.1.6.1
Raise to the power of .
Step 2.4.2.1.6.2
Raise to the power of .
Step 2.4.2.1.6.3
Use the power rule to combine exponents.
Step 2.4.2.1.6.4
Add and .
Step 2.4.2.1.6.5
Raise to the power of .
Step 2.4.2.1.6.6
Raise to the power of .
Step 2.4.2.1.6.7
Use the power rule to combine exponents.
Step 2.4.2.1.6.8
Add and .
Step 2.4.2.2
If any individual factor on the left side of the equation is equal to , the entire expression will be equal to .
Step 2.4.2.3
Set equal to and solve for .
Tap for more steps...
Step 2.4.2.3.1
Set equal to .
Step 2.4.2.3.2
Solve for .
Tap for more steps...
Step 2.4.2.3.2.1
Set the equal to .
Step 2.4.2.3.2.2
Add to both sides of the equation.
Step 2.4.2.4
Set equal to and solve for .
Tap for more steps...
Step 2.4.2.4.1
Set equal to .
Step 2.4.2.4.2
Solve for .
Tap for more steps...
Step 2.4.2.4.2.1
Set the equal to .
Step 2.4.2.4.2.2
Subtract from both sides of the equation.
Step 2.4.2.5
The final solution is all the values that make true.
Step 2.5
The final solution is all the values that make true.
Step 3