1_2 Expressions with Variables

Example 1

Substitute 4 for x and evaluate:(11 - x)*5.
Write these steps: Think these reasons:
Write the given expression. (11 - x)*5 The next step is the substitution.
Substitute. = (11 - 4) * 5 Now evaluate the expression. There is nothing to add, but one can subtract 4 from 11.
Subtract. = 7 * 5 Next, evaluate the multiplilcation.
Multiply. = 35 Next, indicate that this is the answer.
Underline the answer.




Example 2

Evaluate x - 10 / 2, if x is 20.
Write these steps: Think these reasons:
Write the given expression. x - 10 / 2 The next step is the substitution of x.
Substitute. = 20 - 10 / 2 Now evaluate the expression. There is nothing to multiply, but one can divide 10 by 2.
Divide. = 20 - 5 Next evaluate the subtration.
Subtract. = 15 Next indicate that this is the answer.
Underline the answer.




Algebra Section 1_2
Exercises

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