Math Pacing
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Solving Equations and Formulas
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Solving Equations and Formulas
Solving Equations and Formulas
Some equations such as the one on the previous slide contain more than one variable.
At times, you will need to solve these equations for one of the variables.
Solve for b.
Original equation
Simplify.
Subtract 12c from each side.
Divide each side by 5.
Solve and Equation for a Specific Variable
or
Simplify.
Answer: The value of b is .
Solve and Equation for a Specific Variable
Solve for y.
Answer: The value of y is .
Solve and Equation for a Specific Variable
Do this one in your notes, please!
Add 17y to both sides
Subtract 13 from both sides
Divide both sides by 17
Solving Equations and Formulas
Many real-world problems require the use of formulas.
Sometimes solving a formula for a specific variable will help you solve the problem.
Fuel Economy A car’s fuel economy E (miles per
gallon) is given by the formula , where m is
the number of miles driven and g is the number of
gallons of fuel used. Solve the formula for m.
Use a Formula to Solve a Problem
Formula for fuel economy.
Simplify.Answer:
Multiply each side by g.
Use a Formula to Solve a Problem
Fuel Economy If Claudia’s car has an average fuel consumption of 30 miles per gallon and she used 9.5 gallons, how far did she drive?
Formula for how many miles driven
E = 30 mpg and g = 9.5 gallons
Multiply.
Answer: She drove 285 miles.
Use a Formula to Solve a Problem
Fuel Economy A car’s fuel economy E (miles per
gallon) is given by the formula , where m is
the number of miles driven and g is the number of
gallons of fuel used. Solve the formula for g.
Answer:
Use a Formula to Solve a Problem
Do this one in your notes, please!
g
mE mgE
E
mg
If Claudia drove 1477 miles and her pickup has an average fuel consumption of 19 miles per gallon, how many gallons of fuel did she use?
Answer: She used around 77.74 gallons.
Use a Formula to Solve a Problem
Fuel Economy A car’s fuel economy E (miles per
gallon) is given by the formula , where m is
the number of miles driven and g is the number of
gallons of fuel used.
Geometry The formula for the volume of a cylinder is , where r is the radius of the cylinder and h is the height. Solve the formula for h.
Original formula
Answer:
Divide each side by .
Use Dimensional Analysis
Geometry What is the height of a cylindrical swimming pool that has a radius of 12 feet and a volume of 1810 cubic feet?
Answer: The height of the cylindrical swimming pool is about 4 feet.
Formula for h
Use Dimensional Analysis
V = 1810 and r = 12
Use a calculator.
Answer:
Geometry The formula for the volume of a cylinder is , where r is the radius of the cylinder and h is the height.
Solve the formula for r.
Use Dimensional Analysis
Do this one in your notes, please!
What is the radius of a cylindrical swimming pool if the volume is 2010 cubic feet and a height of 6 feet?
Answer: The radius is about 10.3 feet.
Use Dimensional Analysis
Do this one in your notes, please!
2010 = 3.14 • r2 • 6 106.6 ≈ r2