Answer:
12b. 28 = x
12a. -7 = x
11b. -6 = x
11a. 9 = x
10b. UNDEFINED
10a. -⅕ = x
9b. i = x
9a. ±3 = x
Explanation:
12. Cube both sides of both equations, then solve for x:
![12b. \: 3 = \sqrt[3]{x - 1} >> 27 = x - 1 \\ \\ 28 = x \\ \\ 12a. \: -2 = \sqrt[3]{x - 1} >> -8 = x - 1 \\ \\ -7 = x](https://img.qammunity.org/2020/formulas/mathematics/high-school/zyuq3s7q0acyt00jbk02mi3mk6b8bcmgzp.png)
11. Square both sides of both equations, then solve for x:
![11b. \: 1 = √(x + 7) >> 1 = x + 7 \\ \\ -6 = x \\ \\ 11a. \: 4 = √(x + 7) >> 16 = x + 7 \\ \\ 9 = x](https://img.qammunity.org/2020/formulas/mathematics/high-school/4d20kl8gm70l23uuppwwu7x0mcivdjb0rx.png)
10. Dividing is the same as multiplying by the multiplicative inverse of another term:
![10a. \: -5 = (1)/(x) >> -5 = {x}^( -1) \\ \\ -(1)/(5) = x](https://img.qammunity.org/2020/formulas/mathematics/high-school/eayb83991fy1mgsz9v0c6ogmqfaoi4l7jh.png)
* ⁻¹ indicates the multiplicative inverse of -⅕, which is -5. Then there is 1⁄0, which is undefined.
9.
![9b. \: -6 = {x}^(2) - 5](https://img.qammunity.org/2020/formulas/mathematics/high-school/uffqpljr96bim9y21l0gdu7pjgviimc4oz.png)
+ 5 + 5
____________________
-1 = x²
![i = x](https://img.qammunity.org/2020/formulas/mathematics/high-school/ad6u8lecdzflxosylykzzkoefnkg6wsehb.png)
According to the Complex Number System, the iota symbol can be either complex or real:
![√(-1) = i \\ -1 = {i}^(2) \\ -i = {i}^(3) \\ 1 = {i}^(4)](https://img.qammunity.org/2020/formulas/mathematics/high-school/dsi4hbxpltlm2tnwy6fwk1zh1mw0cly6sg.png)
I am joyous to assist you anytime.