f of x = the square root of 2x minus 5

Find f (27)
A. 2
B. 3
C. -5
D. 7
D
not sure on this stuff, could you explain the steps?

just substitute in the value for x:

If f(x) = √(2x-5),
f(27) = √(2*27 - 5) = √(54-5) = √49 = 7