Explanation:
Well the first 3 you just plug in the value of x which results in.
a. f(0) = 7(0)^2 + 3(0) - 2
f(0) = -2
b. f(2) = 7(2)^2 + 3(2) - 2
f(2) = 7(4) + 6 - 2
f(2) = 28 + 4
f(2) = 32
c. f(-2) = 7(-2)^2 + 3(-2) - 2
f(-2) = 7(4) - 6 - 2
f(-2) = 28 - 8
f(-2) = 20
for the last ones it's essentially the same thing except the value a is not known
d. f(a+1) = 7(a+1)^2 + 3(a+1) - 2
f(a+1) = 7(a^2 + 2a + 1) + 3a + 3 - 2
f(a+1) = 7a^2 +14a + 7 + 3a + 1
f(a+1) = 7a^2 + 17a + 8
c. f(-a) = 7(-a)^2 + 3(a) - 2
f(-a) = 7a^2 + 3a - 2