If $f(x)=x^{2}$. Find (a) $f(x+h)$ (b) $f(x+h)-f(x)$

Step 1 ：Substitute \(x+h\) into the function \(f(x)=x^2\):

Step 2 ：\(f(x+h) = (x+h)^2\)

Step 3 ：Find the difference between \(f(x+h)\) and \(f(x)\):

Step 4 ：\(f(x+h)-f(x) = (x+h)^2 - x^2\)

Step 5 ：\boxed{\text{Final Answer:}}\

Step 6 ：(a) \boxed{f(x+h) = (x+h)^2}\

Step 7 ：(b) \boxed{f(x+h)-f(x) = (x+h)^2 - x^2}\