Question

Solve 4x2 = 12x + 40 by factoring.
If you don't mind show the steps please...(:

Answer 1

first of all take everything over to the left hand side

4x^2 - 12x - 40 = 0

now everything is a multiple of 4, so start by dividing through by 4 to make the numbers a bit smaller

x^2 - 3x - 10 = 0

now.. you need to think of two numbers that:
multiply to give you -10
add to give you -3

can you think of them? it's -5 and 2 (remember that + x - = -)

so the brackets are:

(x - 5)(x + 2) = 0

now... if two numbers multiplied together are zero one of them MUST be zero....
my medal