if k(x)=x2-3x, the value of k(3+h) is?

Answer 1

substitute 3+h for x and you'll get

k(3+h) = (3+h)^2 - 3(3+h)

= 9 + 6h + h^2 - 9 - 3h

=3h + h^2

Answer 2

k(3 + h) = (3 + h)^2 - 3(3 + h)
k(3 + h) = ((3 + h)(3 + h)) - 9 - 3h
k(3 + h) = (9 + 3h + 3h + h^2) - 9 - 3h
k(3 + h) = 9 + 6h + h^2 - 9 - 3h
k(3 + h) = h^2 + 3h

another way to do this is

k(x) = x^2 - 3x
k(x) = x(x - 3)

k(3 + h) = (3 + h)((3 + h) - 3)
k(3 + h) = (3 + h)(3 + h - 3)
k(3 + h) = (3 + h)h
k(3 + h) = h^2 + 3h