Chapter 1.8, Problem 63PPE

To determine

The solution of the equation $-4a=48$ , and check the solution.

Answer to Problem 63PPE

  $a=-12$

Explanation of Solution

Given:

The equation, $-4a=48$ .

Concept Used:

• To get rid of a number in addition from one side, subtract the same number from both sides of equal sign.
• To get rid of a number in subtraction from one side, add the same number both sides of equal sign.
• To get rid of a number in multiplication from one side, divide the same number from both sides of equal sign.
• To get rid of a number in division from one side, multiply the same number both sides of equal sign.

Rules of Addition/ Subtraction:

• Two numbers with similar sign always get added and the resulting number will carry the similar sign.
• Two numbers with opposite signs always get subtracted and the resulting number will carry the sign of larger number.

Rules of Multiplication/ Division:

• The product/quotient of two similar sign numbers is always positive.
• The product/quotient of two numbers with opposite signs is always negative.

Calculation:

In order to solve the given equation $-4a=48$ for the unknown variable, isolate the variable term a on one side by performing some basic algebraic operations to get rid of the other numbers and terms associated with it.

Here to isolate a on left side, first divide both sides by $-4$ to get rid of it from left side and then simplify further as shown below,

  $\begin{array}{c}-4a=48\\ \frac{-4a}{-4}=\frac{48}{-4}\\ a=-12\end{array}$

Thus, the solution of the given equation is $a=-12$ .

Now, to check the solution, substitute $a=-12$ in the given equation and check whether the values on both sides of equal sign is same or no. So, it gives

  $\begin{array}{c}-4a=48\\ -4\left(-12\right)=48\\ 48=48\text{True Statement}\end{array}$

Since, the left hand side and right hand side are equal, so the solution is correct.