chapter 1 – tools of algebra 1.5 – rewriting equations and formulas
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Chapter 1 – Tools of Algebra
1.5 – Rewriting Equations and Formulas
1.5 – Rewriting Equations and Formulas
In this section we will review:Rewriting common formulas and
equations that have more than one variable
1.5 – Rewriting Equations and Formulas
When an equation has more than one variable, you can solve for ANY of the variables.
1.5 – Rewriting Equations and Formulas
Common formulasDistance
• d = rt• d = distance, r = rate, t = time
Simple Interest• I = Prt• I = interest, P = principle, r = rate, t = time
1.5 – Rewriting Equations and Formulas
Common formulasTemperature
• F = 9/5 C + 32• F = degrees Fahrenheit, C = degrees Celsius
1.5 – Rewriting Equations and Formulas Geometry Formulas
Rectangle• Perimeter
• P = 2l + 2w
• Area• A = lw
Triangle• Perimeter
• P = a + b + c
• Area• A = ½ bh
1.5 – Rewriting Equations and Formulas
Geometry FormulasTrapezoid
• Area• A = ½ (b1 + b2)h
Circle• Circumference
• C = πd or C = 2πr
• Area• A = πr2
1.5 – Rewriting Equations and Formulas
Example 1Solve the formula F = ma for a.
1.5 – Rewriting Equations and Formulas
Example 2Solve the formula PE = mgh for h.
1.5 – Rewriting Equations and Formulas Example 3
A conservationist wants to survey a circular lake but cannot measure the diameter of the lake directly. Instead, the conservationist measures the circumference. It is 2 1/3 miles. What is the diameter of the lake, to the nearest ¼ mile?
1.5 – Rewriting Equations and Formulas
Example 4Find the value of y in the equation
3x + 4y = 10 when x = -2 and when x = 6.
1.5 – Rewriting Equations and Formulas
Example 5 A campus bookstore sells T-shirts for $15
each and sweatshirts for $22 each. Write an equation with more than one variable for the bookstore’s revenue R from selling m T-shirts and n sweatshirts.
1.5 – Rewriting Equations and Formulas
Example 6 If the campus bookstore needs to have
$6600 in revenue from sales of these two items. What are some combinations of T-shirts and sweatshirts that will meet this objective?
1.5 – Rewriting Equations and Formulas
HOMEWORK
Worksheet 1.5
#1 – 3, 13 – 25 all