Algebra 1 Section 2.2

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Evaluating an Expression Substitute the given values for the variables. Evaluate by following the order of operations.

Example 1 Evaluate 3a2 - b + c3 when a = 1, b = 4, and c = 3. 3(1)2 - 4 + 33 3 - 4 + 27 26

Example 2 Evaluate x2yz2 when x = -½, y = -2, and z = ¼. 1 4 -2 16 • • -1 1 4 -2 16 • • x2yz2 (-½)2(-2)(¼)2 2 1 32 -

Definition A formula is an equation that expresses the relationship between related quantities. 9 5 F = C + 32 p = 0.433h

Definition Formulas are mathematical sentences that are used extensively in many professions.

Math Verbs =  ≈   is, equals is not equal to is approximately equal to is a subset of is an element of

Math Verbs  > < is not an element of is greater than is less than is at least is at most

Perimeter and Area Formulas Rectangle p = 2l + 2w A = lw Square p = 4s A = s2

Perimeter and Area Formulas Circle c = 2r A = r 2 Triangle p = a + b + c A = ½bh

Example 3 Find the perimeter of a rectangle whose length is 8 cm and whose width is 3 cm. p = 2l + 2w p = 2(8) + 2(3) p = 16 + 6 p = 22 cm

Example 4 Find the area of a circle with a radius of 9 ft. A =  r 2 A = 254.34 ft2

Using Formulas Write the correct formula. Substitute the given values for the variables in the formula. Evaluate the expression.

Homework: pp. 53-55