Please help Write the series using summation notation.

4. - 10 + 2 + 14 + 26 + 38 + 50 + 62 + 74

5. 6+13+32+69+

6. - 5/8 + 10/11 + 20/16 + 40/23

Find the gradient of f(x,y,z)equals=left parenthesis x squared plus y squared plus z squared right parenthesis superscript negative 1 divided by 2 baseline plus ln left parenthesis x right parenthesis x2+y2+z2−1/2+ln(xyz) at the point left parenthesis negative 2 comma 1 comma negative 2 right parenthesis(−2,1,−2).

What are “like terms”? why can we only add like terms?

How do i take any fraction and make it into a decimal or percentage?