To prove that Amy's answer to the equation is correct, we can use two methods:
First, we can use the quadratic formula and find the solutions. Then compare these with Amy's answer.
Second, we can perform checking on which we substitute each in the problem and result should be equal to zero.
Let us use the second option, perform checking for x=7/2.
2X²+ 5X-42=0
2*(7/2)² +5(7/2) - 42=0
24.5+15.5 - 42=0
42-42=0
0=0
Perform checking for x= -6
2(-6)²+5*(-6) -42=0
72-30-42=0
42-42=0
0=0
Therefore, Amy's answer is correct.