Answer :
Put 5 where x is and do the arithmetic.
f(5) = 5^2 +2*5
f(5) = 25 +10 . . . . . evaluate the products
f(5) = 35 . . . . . . . . evaluate the sum
f(5) = 5^2 +2*5
f(5) = 25 +10 . . . . . evaluate the products
f(5) = 35 . . . . . . . . evaluate the sum