4. (x+h)3=x3+3h x2+3h2 x+h3.
6. (x+h)4=x4+4h x3+6h2 x2+4h3 x+h4.
7. The gradient is 4x3.
9.
(i) 4x;
(ii) 34 x;
(iii) -2x;
(iv) 2a x;
(v) 6x2;
(vi) 3a x2;
(vii) n a xn-1.
10. You should see that you get the gradient of y=x3 plus the gradient
of y=x2. Similarly, the gradient of y=xn+xm is just the gradient of
y=xn plus the gradient of y=xm, that is, n xn-1+m xm-1.