Algebra Examples

$2 x^{2} - x - 15$

Step 1

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 $a \cdot c = 2 \cdot - 15 = - 30$ and whose sum is $b = - 1$ .

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Step 1.1

Factor $- 1$ out of $- x$ .

$2 x^{2} - (x) - 15$

Step 1.2

Rewrite $- 1$ as $5$ plus $- 6$

$2 x^{2} + (5 - 6) x - 15$

Step 1.3

Apply the distributive property.

$2 x^{2} + 5 x - 6 x - 15$

Step 2

Factor out the greatest common factor from each group.

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Step 2.1

Group the first two terms and the last two terms.

$(2 x^{2} + 5 x) - 6 x - 15$

Step 2.2

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

$x (2 x + 5) - 3 (2 x + 5)$

Step 3

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

$(2 x + 5) (x - 3)$