Question

Solve x2 − 8x − 20 = 0.

x = 4, x = −5

x = −4, x = 5

x = 2, x = −10

x = −2, x = 10

Answer 1

I suggest that solving by factoring is a good idea here.

Answer 2

A good start to solving this particular problem is of course — factoring. We start it by:

\(\Rightarrow x^2 - 10x + 2x + 20 = 0 \)

Answer 3

Then group it.

\(\Rightarrow x(x - 10) + 2(x - 10) = 0\)
\(\Rightarrow (x + 2)( x - 10) = 0\)