Precalculus Examples

$f (x) = x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 x^{3} \cdot (28 x^{2}) - 8 x + 1$

Step 1

Set $x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 x^{3} \cdot (28 x^{2}) - 8 x + 1$ equal to $0$ .

$x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 x^{3} \cdot (28 x^{2}) - 8 x + 1 = 0$

Step 2

Solve for $x$ .

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Step 2.1

Simplify $x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 x^{3} \cdot (28 x^{2}) - 8 x + 1$ .

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Step 2.1.1

Simplify each term.

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Step 2.1.1.1

Rewrite using the commutative property of multiplication.

$x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 \cdot 28 x^{3} x^{2} - 8 x + 1 = 0$

Step 2.1.1.2

Multiply $x^{3}$ by $x^{2}$ by adding the exponents.

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Step 2.1.1.2.1

Move $x^{2}$ .

$x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 \cdot 28 (x^{2} x^{3}) - 8 x + 1 = 0$

Step 2.1.1.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 \cdot 28 x^{2 + 3} - 8 x + 1 = 0$

Step 2.1.1.2.3

Add $2$ and $3$ .

$x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 60 \cdot 28 x^{5} - 8 x + 1 = 0$

Step 2.1.1.3

Multiply $60$ by $28$ .

$x^{8} + 8 x^{7} - 28 x^{6} - 60 x^{5} + 70 x^{4} + 1680 x^{5} - 8 x + 1 = 0$

Step 2.1.2

Add $- 60 x^{5}$ and $1680 x^{5}$ .

$x^{8} + 8 x^{7} - 28 x^{6} + 1620 x^{5} + 70 x^{4} - 8 x + 1 = 0$

Step 2.2

Graph each side of the equation. The solution is the x-value of the point of intersection.

$x \approx - 0.30016422$

Step 3