Solve by Factoring 5x^2+8x-4=0

$5 x^{2} + 8 x - 4 = 0$

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 $a \cdot c = 5 \cdot - 4 = - 20$ and whose sum is $b = 8$ .

Factor $8$ out of $8 x$ .

$5 x^{2} + 8 (x) - 4 = 0$

Rewrite $8$ as $- 2$ plus $10$

$5 x^{2} + (- 2 + 10) x - 4 = 0$

Apply the distributive property.

$5 x^{2} - 2 x + 10 x - 4 = 0$

Factor out the greatest common factor from each group.

Group the first two terms and the last two terms.

$(5 x^{2} - 2 x) + 10 x - 4 = 0$

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

$x (5 x - 2) + 2 (5 x - 2) = 0$

Factor the polynomial by factoring out the greatest common factor, $5 x - 2$ .

$(5 x - 2) (x + 2) = 0$

Step 2

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

$5 x - 2 = 0$

$x + 2 = 0$

Step 3

Set $5 x - 2$ equal to $0$ and solve for $x$ .

Set $5 x - 2$ equal to $0$ .

$5 x - 2 = 0$

Solve $5 x - 2 = 0$ for $x$ .

Add $2$ to both sides of the equation.

$5 x = 2$

Divide each term in $5 x = 2$ by $5$ and simplify.

Divide each term in $5 x = 2$ by $5$ .

$\frac{5 x}{5} = \frac{2}{5}$

Simplify the left side.

Cancel the common factor of $5$ .

Cancel the common factor.

$\frac{5 x}{5} = \frac{2}{5}$

Divide $x$ by $1$ .

$x = \frac{2}{5}$

Step 4

Set $x + 2$ equal to $0$ and solve for $x$ .

Set $x + 2$ equal to $0$ .

$x + 2 = 0$

Subtract $2$ from both sides of the equation.

$x = - 2$

Step 5

The final solution is all the values that make $(5 x - 2) (x + 2) = 0$ true.

$x = \frac{2}{5}, - 2$

Solve by Factoring 5x^2+8x-4=0

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