How do you factor $15x^2 - 5x - 10$ ?

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Answer 1 · 2016-01-05T17:44:38

$=color(blue)( (15x+10)(x-1)$

$15x^2 -5x-10$

We can Split the Middle Term of this expression to factorise it.

In this technique, if we have to factorise an expression like $ax^2 + bx + c$ , we need to think of 2 numbers such that:

$N_1*N_2 = a*c = 15*-10 = -150$
AND
$N_1 +N_2 = b = -5$

After trying out a few numbers we get $N_1 = -15$ and $N_2 =10$
$10*-15 = -150$ , and $10+(-15)= -5$

$15x^2 -5x-10 =15x^2 -15x +10x-10$

$= 15x(x-1) +10 (x-1)$

$(x-1)$ is a common factor to each of the terms

$=color(blue)( (15x+10)(x-1)$

How do you factor 15x^2 - 5x - 1015x^2 - 5x - 10?