Chapter 8.2, Problem 11GP

To determine

The solution of the equation $-\frac{1}{8}x-5=-1$ , and check the solution.

Answer to Problem 11GP

  $x=-36$

Explanation of Solution

Given:

The equation, $-\frac{1}{8}x-5=-1$ .

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 $-\frac{1}{8}x-5=-1$ for the unknown variable, isolate the variable term x on one side by performing some basic algebraic operations to get rid of the other numbers and terms associated with it.

Here to isolate x on left side, first add 5 both sides and then multiply both sides by -8 and then simplify further as shown below,

  $\begin{array}{l}-\frac{1}{8}x-5=-1\\ -\frac{1}{8}x-5+5=-1+5\\ -\frac{1}{8}x=4\\ -\frac{1}{8}x\times \left(-8\right)=4\times \left(-8\right)\\ x=-36\end{array}$

Thus, the solution of the given equation is $x=-36$ .

Now, to check the solution, substitute $x=-36$ in the given equation and check whether the values on both sides of equal sign is same or no. So, it gives

  $\begin{array}{l}-\frac{1}{8}x-5=-1\\ -\frac{1}{8}\left(-36\right)-5=-1\\ 4-5=-1\\ -1=-1\text{True Statement}\end{array}$

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