Precalculus Examples
1212 , 33
Step 1
Roots are the points where the graph intercepts with the x-axis (y=0)(y=0).
y=0y=0 at the roots
Step 2
The root at x=12x=12 was found by solving for xx when x-(12)=yx−(12)=y and y=0y=0.
The factor is x-12x−12
Step 3
The root at x=3x=3 was found by solving for xx when x-(3)=yx−(3)=y and y=0y=0.
The factor is x-3x−3
Step 4
Combine all the factors into a single equation.
y=(x-12)(x-3)y=(x−12)(x−3)
Step 5
Step 5.1
Expand (x-12)(x-3)(x−12)(x−3) using the FOIL Method.
Step 5.1.1
Apply the distributive property.
y=x(x-3)-12⋅(x-3)y=x(x−3)−12⋅(x−3)
Step 5.1.2
Apply the distributive property.
y=x⋅x+x⋅-3-12⋅(x-3)y=x⋅x+x⋅−3−12⋅(x−3)
Step 5.1.3
Apply the distributive property.
y=x⋅x+x⋅-3-12x-12⋅-3y=x⋅x+x⋅−3−12x−12⋅−3
y=x⋅x+x⋅-3-12x-12⋅-3y=x⋅x+x⋅−3−12x−12⋅−3
Step 5.2
Simplify and combine like terms.
Step 5.2.1
Simplify each term.
Step 5.2.1.1
Multiply x by x.
y=x2+x⋅-3-12x-12⋅-3
Step 5.2.1.2
Move -3 to the left of x.
y=x2-3⋅x-12x-12⋅-3
Step 5.2.1.3
Combine x and 12.
y=x2-3x-x2-12⋅-3
Step 5.2.1.4
Multiply -12⋅-3.
Step 5.2.1.4.1
Multiply -3 by -1.
y=x2-3x-x2+3(12)
Step 5.2.1.4.2
Combine 3 and 12.
y=x2-3x-x2+32
y=x2-3x-x2+32
y=x2-3x-x2+32
Step 5.2.2
To write -3x as a fraction with a common denominator, multiply by 22.
y=x2-3x⋅22-x2+32
Step 5.2.3
Combine -3x and 22.
y=x2+-3x⋅22-x2+32
Step 5.2.4
Combine the numerators over the common denominator.
y=x2+-3x⋅2-x2+32
Step 5.2.5
To write x2 as a fraction with a common denominator, multiply by 22.
y=x2⋅22+-3x⋅2-x2+32
Step 5.2.6
Combine x2 and 22.
y=x2⋅22+-3x⋅2-x2+32
Step 5.2.7
Combine the numerators over the common denominator.
y=x2⋅2-3x⋅2-x2+32
Step 5.2.8
Combine the numerators over the common denominator.
y=x2⋅2-3x⋅2-x+32
y=x2⋅2-3x⋅2-x+32
Step 5.3
Simplify the numerator.
Step 5.3.1
Move 2 to the left of x2.
y=2⋅x2-3x⋅2-x+32
Step 5.3.2
Multiply 2 by -3.
y=2x2-6x-x+32
Step 5.3.3
Subtract x from -6x.
y=2x2-7x+32
Step 5.3.4
Factor by grouping.
Step 5.3.4.1
For a polynomial of the form ax2+bx+c, rewrite the middle term as a sum of two terms whose product is a⋅c=2⋅3=6 and whose sum is b=-7.
Step 5.3.4.1.1
Factor -7 out of -7x.
y=2x2-7x+32
Step 5.3.4.1.2
Rewrite -7 as -1 plus -6
y=2x2+(-1-6)x+32
Step 5.3.4.1.3
Apply the distributive property.
y=2x2-1x-6x+32
y=2x2-1x-6x+32
Step 5.3.4.2
Factor out the greatest common factor from each group.
Step 5.3.4.2.1
Group the first two terms and the last two terms.
y=(2x2-1x)-6x+32
Step 5.3.4.2.2
Factor out the greatest common factor (GCF) from each group.
y=x(2x-1)-3(2x-1)2
y=x(2x-1)-3(2x-1)2
Step 5.3.4.3
Factor the polynomial by factoring out the greatest common factor, 2x-1.
y=(2x-1)(x-3)2
y=(2x-1)(x-3)2
y=(2x-1)(x-3)2
Step 5.4
Expand (2x-1)(x-3) using the FOIL Method.
Step 5.4.1
Apply the distributive property.
y=2x(x-3)-1(x-3)2
Step 5.4.2
Apply the distributive property.
y=2x⋅x+2x⋅-3-1(x-3)2
Step 5.4.3
Apply the distributive property.
y=2x⋅x+2x⋅-3-1x-1⋅-32
y=2x⋅x+2x⋅-3-1x-1⋅-32
Step 5.5
Simplify and combine like terms.
Step 5.5.1
Simplify each term.
Step 5.5.1.1
Multiply x by x by adding the exponents.
Step 5.5.1.1.1
Move x.
y=2(x⋅x)+2x⋅-3-1x-1⋅-32
Step 5.5.1.1.2
Multiply x by x.
y=2x2+2x⋅-3-1x-1⋅-32
y=2x2+2x⋅-3-1x-1⋅-32
Step 5.5.1.2
Multiply -3 by 2.
y=2x2-6x-1x-1⋅-32
Step 5.5.1.3
Rewrite -1x as -x.
y=2x2-6x-x-1⋅-32
Step 5.5.1.4
Multiply -1 by -3.
y=2x2-6x-x+32
y=2x2-6x-x+32
Step 5.5.2
Subtract x from -6x.
y=2x2-7x+32
y=2x2-7x+32
Step 5.6
Split the fraction 2x2-7x+32 into two fractions.
y=2x2-7x2+32
Step 5.7
Split the fraction 2x2-7x2 into two fractions.
y=2x22+-7x2+32
Step 5.8
Cancel the common factor of 2.
Step 5.8.1
Cancel the common factor.
y=2x22+-7x2+32
Step 5.8.2
Divide x2 by 1.
y=x2+-7x2+32
y=x2+-7x2+32
Step 5.9
Move the negative in front of the fraction.
y=x2-7x2+32
y=x2-7x2+32
Step 6