Consider the function f(x) = x^2 +2sqrt(x). Evaluate 2f(2) - f(8)
f(2) = 2^2 + 2sqrt (2) = 4 + 2sqrt (2)
2f(2) = 8 + 4sqrt (2)
f(8) = 8^2 + 2sqrt (8) = 64 + 2*2sqrt (2) = 64 + 4sqrt (2)
2f(2) - f(8) =
(8 + 4sqrt (2) ) - ( 64 + 4sqrt(2) ) = - 56