Chapter 1.8, Problem 6P

To determine

The solution of the equation $\frac{u}{8}=-4$ , and check the solution.

Answer to Problem 6P

  $u=-32$

Explanation of Solution

Given:

The equation, $\frac{u}{8}=-4$ .

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 $\frac{u}{8}=-4$ for the unknown variable, isolate the variable term u on one side by performing some basic algebraic operations to get rid of the other numbers and terms associated with it.

Here to isolate u on left side, first multiply both sides by $8$ to get rid of it from denominator on left side and then simplify further as shown below,

  $\begin{array}{c}\frac{u}{8}=-4\\ \frac{u}{8}\cdot 8=-4\cdot 8\\ u=-32\end{array}$

Thus, the solution of the given equation is $u=-32$ .

Now, to check the solution, substitute $u=-32$ in the given equation and check whether the values on both sides of equal sign is same or no. So, it gives

  $\begin{array}{c}\frac{u}{8}=-4\\ \frac{-32}{8}=-4\\ -4=-4\text{True Statement}\end{array}$

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