Question

Can anyone help me with #85?

Answer 1

Part (a)

`\overline{x}=(\sum x)/(n) \\ \\ \boxed{\sum x=n\overline{x}}`

Part (b)

`\sum x^2-2\overline{x}(n\overline{x})+n\overline{x}^2 \\ \\ =\sum x^2 -2n\overline{x}^2+n\overline{x}^2 \\ \\ =\boxed{\sum x^2-n\overline{x}^2}`