What is the solution set of x2-x-20 equals 0?

Answer 1

Given the equation x2 - x - 20 = 0, we see that it can likely be factored easily. Through simple trial and error we find that:

(x - 5)(x + 4) = 0.

From here, we set both terms equal to zero to find all possible solutions.

x - 5 = 0

x = 5

and

x + 4 = 0

x = -4.

Substituting 5 and -4 back into the original equation yield true results. Thus the solution set is x = -4, 5. More formal, the solution set is {-4, 5}.

Note: There are other methods of solving this problem such as the quadratic formula or by graphing the function.