Question

Evaluate the expression when $p=12 \text{and} q=15$.

10. $p + q$

Short answer

The value of the expression p – q is – 3

Step-by-step solution

What is an algebraic expression?

In mathematics, a variable (usually an English alphabet) standing for an unknown value in any equation or Algebraic Expression. In general we used x, y, z or t (time) , d (distance) and r for radius.

Algebraic expressions include at least one variable and at least one operation (addition, subtraction, multiplication, division).

For example, 7(6y + 9z) is an algebraic expression.

Explanation: How to add or subtract the integers.

To add two numbers with the same sign, first add the two numbers ignoring the sign and then put their common sign before the answer.

To add two numbers with the opposite sign, ignore their signs and subtract the smaller number from the bigger number. Then put the sign of the bigger number before the answer.

Example of addition and subtraction.

An example of addition is: 5 + 11 + 3 = 19.

Example: If a = 7 and b = 8, find the value of a + b and a – b

To evaluate the expressiona + b, substitute the value of a as 7 and the value of b as 8 and add the numbers as shown below,

$a+b = 7+8=15$;$a-b=7-8=-1$

Evaluate the expression p - q when p = 12 and q = 15 

Rule:To add two numbers with the opposite sign, ignore their signs and subtract the smaller number from the bigger number. Then put the sign of the bigger number before the answer.

To evaluate the expression(p - q), substitute the value of p as 12; q = 15 and subtract 12 from 15 and put the sign of 15 before the answer as 15 is the bigger number with negative sign.

When p = 12; q = 15 and the expression (p – q) is $\text{p} - \text{q} \text{=} \text{12} - \text{15} \text{=} - 3$

Thus, the value of the expression is – 3.