Q10. - Algebra 1

Question

Solve each equation. Check your solution. 

$-21=7-4y$

Step-by-Step Solution

Answer

The solution of given equation is $y=7$.

Step 1. Given equation.

$-21=7-4y$

Step 2. Description of step.

Solve the given equation to find the value of y as,

 

$\begin{array}{c}-21=7-4y\\ \Rightarrow -21-7=-4y\\ \Rightarrow -28=-4y\\ \Rightarrow 4y=28\\ \Rightarrow y=\frac{28}{4}\\ \Rightarrow y=7\end{array}$

Step 3. Check solution.

In order to check the solution, put the value of y back in the given equation and see if it satisfies the equation, i.e. of left hand side is equals to right hand side, as: 

$\begin{array}{c}-21=7-4y\\ \Rightarrow -21=7-4\left(7\right)\\ \Rightarrow -21=7-28\\ \Rightarrow -21=-21\\ \Rightarrow \text{true}\end{array}$

Hence, the solution $y=7$ satisfies the equation.