How do you factor n25n+6?

1 Answer
May 16, 2015

Notice that 5=2+3 and 6=23, so

(n2)(n3)=(nn)(2n)(3n)+(23)

=n2(2+3)n+(23)

=n25n+6

In general (x+a)(x+b)=x2+(a+b)x+ab so if you can spot two numbers a and b such that their sum is the coefficient of x and their product is the constant term then you can quickly factorise such a quadratic formula.