a) Replace x by 0 and simplify:
f(0) = 2(0) + 1 = 0 + 1 = 1
Hence, f(0) = 1
b) Replace x by -3 and simplify:
f(-3) = 2(-3) + 1 = -6 + 1 = -5
Hence, f(-3) = -5
c) Replace x by 2x+3 and simplify:
f(2x+1) = 2(2x + 1) + 1 = 4x + 2 + 1 = 4x + 3
Hence, f(2x+1) = 4x + 3