Question

Which shows the zeros of f(x) = x^2 - x - 2?

a. 1 and 2
b. -1 and -2
c. 1 and -2
d. 2 and -1

Answer 1

d. 2 and -1

Explanation:

`f(x)=x^2-x-2\\\\\text{The zeros are for}\ f(x)=0:\\\\x^2-x-2=0\\\\x^2-2x+x-2=0\\\\x(x-2)+1(x-2)=0\\\\(x-2)(x+1)=0\iff x-2=0\ \vee\ x+1=0\\\\x-2=0\qquad\text{add 2 to both sides}\\x=2\\\\x+1=0\qquad\text{subtract 1 from both sides}\\x=-1`