Mathematica won't plot my functions again. Why is this happening?

Questions
1

In the file I have attached, I have h(x) defined as h[x_]:=x^2 - 4x + 7cos[x] and I have tried to plot it and as you can see from the images, I get an empty graph. Why is this? And can someone help me fix it?

2

Hi Melissa–

Cosine has to be spelled with t capitol “C”. All built-in Mathematica functions start with a capitol.

when you define the function as

h[x_] := x^2 - 4 x + 7 Cos[x]

things work fine.