Solve by Factoring 8x^2-30x-27=0

$8 x^{2} - 30 x - 27 = 0$

Step 1

Factor by grouping.

For a polynomial of the form $a x^{2} + b x + c$ , rewrite the middle term as a sum of two terms whose product is $a \cdot c = 8 \cdot - 27 = - 216$ and whose sum is $b = - 30$ .

Factor $- 30$ out of $- 30 x$ .

$8 x^{2} - 30 x - 27 = 0$

Rewrite $- 30$ as $6$ plus $- 36$

$8 x^{2} + (6 - 36) x - 27 = 0$

Apply the distributive property.

$8 x^{2} + 6 x - 36 x - 27 = 0$

Factor out the greatest common factor from each group.

Group the first two terms and the last two terms.

$(8 x^{2} + 6 x) - 36 x - 27 = 0$

Factor out the greatest common factor (GCF) from each group.

$2 x (4 x + 3) - 9 (4 x + 3) = 0$

Factor the polynomial by factoring out the greatest common factor, $4 x + 3$ .

$(4 x + 3) (2 x - 9) = 0$

Step 2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$4 x + 3 = 0$

$2 x - 9 = 0$

Step 3

Set $4 x + 3$ equal to $0$ and solve for $x$ .

Set $4 x + 3$ equal to $0$ .

$4 x + 3 = 0$

Solve $4 x + 3 = 0$ for $x$ .

Subtract $3$ from both sides of the equation.

$4 x = - 3$

Divide each term in $4 x = - 3$ by $4$ and simplify.

Divide each term in $4 x = - 3$ by $4$ .

$\frac{4 x}{4} = \frac{- 3}{4}$

Simplify the left side.

Cancel the common factor of $4$ .

Cancel the common factor.

$\frac{4 x}{4} = \frac{- 3}{4}$

Divide $x$ by $1$ .

$x = \frac{- 3}{4}$

Simplify the right side.

Move the negative in front of the fraction.

$x = - \frac{3}{4}$

Step 4

Set $2 x - 9$ equal to $0$ and solve for $x$ .

Set $2 x - 9$ equal to $0$ .

$2 x - 9 = 0$

Solve $2 x - 9 = 0$ for $x$ .

Add $9$ to both sides of the equation.

$2 x = 9$

Divide each term in $2 x = 9$ by $2$ and simplify.

Divide each term in $2 x = 9$ by $2$ .

$\frac{2 x}{2} = \frac{9}{2}$

Simplify the left side.

Cancel the common factor of $2$ .

Cancel the common factor.

$\frac{2 x}{2} = \frac{9}{2}$

Divide $x$ by $1$ .

$x = \frac{9}{2}$

Step 5

The final solution is all the values that make $(4 x + 3) (2 x - 9) = 0$ true.

$x = - \frac{3}{4}, \frac{9}{2}$

Solve by Factoring 8x^2-30x-27=0

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