4x^2-20x=0

Question

solve the equation

x=...........

x=...........

Answer 1

Hi Katie;

4x²-20x=0

We need to factor...

4x(x-5)=0

Either 4x or (x-5) equals 0.

If 4x=0, then x=0

If x-5=0, then x=5

Or...

We can factor like this...

4x²-20x=0

(4x-0)(x-5)

If we FOIL...

FIRST...(4x)(x)=4x²

OUTER...(4x)(-5)=-20x

INNER...(0)(x)=0

LAST...(0)(-5)=0

4x²-20x=0

So...

(4x-0)(x-5)

Either parenthetical equation must equal zero.

If 4x-0=0, then x=0

If x-5=0, then x=5

Same result, different factoring approach.