Chapter R.8, Problem 1DE

To determine

To calculate: The value of the expression, $3\cdot \left(-7\right)$.

Answer to Problem 1DE

Solution:

The required value of the expression $3\cdot \left(-7\right)$ is $\underset{\_}{-21}$.

Explanation of Solution

Given information:

The provided expression is $3\cdot \left(-7\right)$.

Formula Used:

Follow the rules below to multiply two real numbers.

Step 1. To multiply two numbers with same sign, multiply the absolute values and make the result positive.

Step 2. To multiply two numbers with different sign, multiply the absolute values and make the result negative.

Step 3. If one number is zero, then its product with some other number is zero.

Calculation:

Consider the provided expression,

$3\cdot \left(-7\right)$

A negative and a positive are multiplied in the above expression.

Now, multiply the absolute values and make the result negative

$7\cdot 3=21$

The result is made negative as below,

$3\cdot \left(-7\right)=-21$

Hence, the value of the expression $3\cdot \left(-7\right)$ is $-21$.