How do you multiply (2x+5)^3?

1 Answer
Apr 7, 2015

If there is (a+b)(c+d) then:

(a+b)(c+d) = a*c + a*d + b*c +b*d

(2x+5)^3 = (2x+5) * (2x+5) * (2x+5)

= [4x^2 + 10x + 10x +25] * (2x+5)

If there is (a+b+c)(d+e) then:

(a+b+c)(d+e) = ad+ae+bd+be+cd+ce

= (4x^2 + 20x + 25) * (2x+5)

=8x^3 + 20x^2 + 40x^2 + 100x + 50x + 125

The answer is:

=8x^3 + 60x^2 + 150x + 15