# How would I factor equations like this? x^2 + 3x + 2. or x^2 - 2x - 15thank you

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Student Comments

neela | Student

There are two quadratic expressions given.

x^2+3x+2 and x^2-2x-15. To find the factors.

1)

To find the factors of x^2+3x+2, we split the middle term 3x into two terms in sich a way that the product of the two split terms equal to the first and last term.

3x is split into two terems 2x + x. Product of the split terms = 2x*x = 2x^2. Product of the 1st and last terms = x^2 * 2 = 2x^2.

Now group the terms and find the common factors (CF) for each group.

(x^2+2x)+(x+2).

x(x+2) +1(x+2). x+2 is the CF.

Take out the CF:

(x+2)(x+1).

2)

x^2-2x-15.

-2x = (-5x)+(3x). And (-5x)*(3x) = x^2*(-15).

Therefore x^2-2x-15 = (x^2 -5x)+(3x-15) = x(x-5)+3(x-5) = (x-5)(x+3).

x^2-2x-15 = (x-5)(x+1).