Question

How to substitute x=-2 and x=5 into 2x^2+6-20=0 to check my work

Answer 1

First answer (x=-2)
...
(2)[(-2)^2]+6-20
2(4)+6-20
8+6-20
14-20
-6 (answer)

Second answer (x=5)
...
(2)[(-5)^2]+6-20
2(25)+6-20
50+6-20
56-20
36 (answer)
Hope this helps!