Example 2 View the prompt below If y 1 evaluate the following expression 14 y

Example 2 view the prompt below if y 1 evaluate the

This preview shows page 37 - 41 out of 91 pages.

Example #2 View the prompt below: If y = 1 , evaluate the following expression: 14 - y 14 - y = 14 - ( 1 ) = 13 If y = 1 , 14 - y = 13 If b = 20 , evaluate the following expression: Copyright © 2018 MindEdge Inc. All rights reserved. Duplication prohibited.
b b b
3.08 Substitution for Multiple Variables Substitution for Multiple Variables We've seen mathematical expressions that have multiple variables. Some examples are: Mathematical Expressions with Multiple Variables x - y -3 a + 3 b 3( P ) · (3 S ) + 1 a 2 + b 2 + c 2 Substitution for One Variable We can use the substitution method on these expressions, similar to an expression containing only one variable. If a variable's value is specified, we can substitute the variable with its value: Using a Calculator for Operations with Multiple Variables When performing operations with known variables, a calculator is a great resource to evaluate expressions and to check your work. Input your operations, including parentheses, to perform calculations. If x = - 4 and y = 9 , what is 8 ( x ) + ( 72 ÷ y ) ? Step 1: Re-write your expression with the knowledge that x = - 4 and y = 9 . 8 ( x ) + ( 72 ÷ y ) = 8 ( -4 ) + ( 72 ÷ 9 ) First perform the operation within the parentheses. Step 2: Perform the operation 72 ÷ 9 on your calculator by typing " 72 ÷ 9 " and then clicking the " = " button. Record the quotient, 8 . Now we see that our expression is equal to 8 ( -4 ) + ( 8 ) . If b = 5 , ( -3a ) + ( 3b ) = ( -3a ) + ( 3 · 5 ) = ( -3a ) + 15 Copyright © 2018 MindEdge Inc. All rights reserved. Duplication prohibited.
You need to clear the screen before entering more information. So, after recording the quotient, click the clear button. Depending on your calculator, this button might say AC , C , CE , or Clear . Step 3: Perform the operation 8 ( -4 ) on your calculator by typing " 8 × -4 " (using the minus sign for negative ) and then clicking = . Record the product, -32 . Now we see that our expression is equal to -32 + ( 8 ) Step 4: Perform the final operation, -32 + 8 , on your calculator by entering " -32 + 8 ." The final answer is -24 . Here, we see that after we substitute b with its value, 5 , the expression is equal to " (-3 a ) + 15 ." Notice that we did not substitute for the variable a because we do not know the value of this variable. Therefore, the variable a remains in the expression, even after evaluation. In the following section, we will explore how to evaluate an expression when multiple variables have known values. Substitution for Multiple Variables When multiple variables each have specified values, we can substitute each variable with its respective value. For example:

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture