For the functions below, find the missing input or output values.

Here are the completed functions:

4.1: Function $y = 2x$
To find $x$, we use $x = \frac{y}{2}$.

• If $y = -6$, $x = \frac{-6}{2} = -3$
• If $y = -4$, $x = \frac{-4}{2} = -2$
• If $y = 2$, $x = \frac{2}{2} = 1$
• If $y = 8$, $x = \frac{8}{2} = 4$ The input values are $\boxed{-3, -2, 1, 4}$.

4.2: Function $n = m - 7$
To find $m$, we use $m = n + 7$.

• If $n = -12$, $m = -12 + 7 = -5$
• If $n = -8$, $m = -8 + 7 = -1$
• If $n = -7$, $m = -7 + 7 = 0$
• If $n = 1$, $m = 1 + 7 = 8$ The input values are $\boxed{-5, -1, 0, 8}$.

4.3: Function $m = n - 2$
To find $m$, we use $m = n - 2$.

• If $n = 2$, $m = 2 - 2 = 0$
• If $n = 6$, $m = 6 - 2 = 4$
• If $n = 8$, $m = 8 - 2 = 6$
• If $n = 20$, $m = 20 - 2 = 18$ The output values are $\boxed{0, 4, 6, 18}$.

4.4: Function $u = 2t + 1$
To find $u$, we use $u = 2t + 1$.

• If $t = 7$, $u = 2(7) + 1 = 14 + 1 = 15$
• If $t = 11$, $u = 2(11) + 1 = 22 + 1 = 23$
• If $t = 27$, $u = 2(27) + 1 = 54 + 1 = 55$
• If $t = -11$, $u = 2(-11) + 1 = -22 + 1 = -21$ The output values are $\boxed{15, 23, 55, -21}$.

4.5: Function $t = -1s + 5$
To find $s$, we rearrange the formula to $s = 5 - t$.

• If $t = -6$, $s = 5 - (-6) = 5 + 6 = 11$
• If $t = -4$, $s = 5 - (-4) = 5 + 4 = 9$
• If $t = 2$, $s = 5 - 2 = 3$
• If $t = 8$, $s = 5 - 8 = -3$ The input values are $\boxed{11, 9, 3, -3}$.

4.6: Function $y = x^2$
To find $x$, we use $x = \sqrt{y}$. (Assuming positive roots as is common in these diagrams unless specified otherwise).

• If $y = 81$, $x = \sqrt{81} = 9$
• If $y = 36$, $x = \sqrt{36} = 6$
• If $y = 16$, $x = \sqrt{16} = 4$
• If $y = 1$, $x = \sqrt{1} = 1$ The input values are $\boxed{9, 6, 4, 1}$.