Answer:
9 . 5/3
10. - 5/11
................................
Part A: the data represent a function because for each value of x, there is a unique value of y.
Part B: from the table, when x = 7, y = 8. from the function f(x) = 2x + 13, f(7) = 2(7) + 13 = 14 + 13 = 27.
Hence f(x) = 2x + 13 has a greater value when x = 7.
Part c: f(x) = 2x + 13 = 75
2x = 75 - 13 = 62
x = 62/2 = 31
I don't understand what you mean by 'mentally' but anyways, here is how to solve it.
(z−12)(z+12)
=(z+−12)(z+12)
=(z)(z)+(z)(12)+(−12)(z)+(−12)(12)
=z^2+12z−12z−144
=z^2−144