Solve AB=A1+(8-1)*3

$$A B = A 1 + ( 8 - 1 ) \cdot 3$$

Solve for A

$$\left\{\begin{matrix}A=\frac{A_{1}+21}{B}\text{, }&B\neq 0\\A\in \mathrm{R}\text{, }&A_{1}=-21\text{ and }B=0\end{matrix}\right.$$

Steps for Solving Linear Equation

Subtract 1 from 8 to get 7.

$$AB=A_{1}+7\times 3$$

Multiply 7 and 3 to get 21.

$$AB=A_{1}+21$$

The equation is in standard form.

$$BA=A_{1}+21$$

Divide both sides by B.

$$\frac{BA}{B}=\frac{A_{1}+21}{B}$$

Dividing by B undoes the multiplication by B.

$$A=\frac{A_{1}+21}{B}$$

Solve for A_1

$$A_{1}=AB-21$$

Solution Steps

Subtract 1 from 8 to get 7.

$$AB=A_{1}+7\times 3$$

Multiply 7 and 3 to get 21.

$$AB=A_{1}+21$$

Swap sides so that all variable terms are on the left hand side.

$$A_{1}+21=AB$$

Subtract 21 from both sides.

$$A_{1}=AB-21$$