How do you factor n^2+2n-15?

2 Answers
May 30, 2015

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

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

N_1*N_2 = 1*-15 = -15
AND
N_1 +N_2 = b = 2

After trying out a few numbers we get N_1 = 5 and N_2 =-3
5*-3= -15, and 5+(-3)= 2

n^2+2n-15 = n^2 + 5n - 3n -15

= n(n+5) - 3(n+5)

(n+5) is a common factor to each of the terms

=color(green)((n+5)(n-3)

May 30, 2015

n^2+2n-15

By factorization:

n^2+color(red)2ncolor(blue)[-15

working rArr -5+3=color(red)2, -5xx3=color(blue)[-15

n^2-5n+3n-15

n(n-5)+3(n-5)

Answer :
color(green)[(n+3)(n-5)