An function is considered to be an even function only if f(-x) = f(x)
1. f(x) = (x-1)^2 = x^2 - 2x + 1
f(-x) = (-x-1)^2 = x^2 + 2x + 1
These two don't match, not an even function
2. f(x) = 8x
f(-x) = -8x
These two don't match, not an even function
3. f(x) = x^2 - x
f(-x) = (-x)^2 - (-x) = x^2 + x
These two don't match, not an even function
4. f(x) = 7
f(-x) = 7
Match, is an even function