Math 71A

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Math 71A

1.5 – Problem Solving and Using Formulas

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ex: Four times the sum of 3 and a number.

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ex: Four times the sum of 3 and a number.

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ex: Four times the sum of 3 and a number.

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ex: Four times the sum of 3 and a number.

ex: 5 less than the quotient of a number and 3.

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ex: Four times the sum of 3 and a number.

ex: 5 less than the quotient of a number and 3.

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ex: Four times the sum of 3 and a number.

ex: 5 less than the quotient of a number and 3.

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sumplus

increased bymore thanadded to

differenceminus

decreased byless than

subtracted from

producttimes

oftwice

quotientdivide

perratio

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sumplus

increased bymore thanadded to

differenceminus

decreased byless than

subtracted from

producttimes

oftwice

quotientdivide

perratio

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

1. Read problem, figure out what it’s asking for, and let represent one of the unknown quantities.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

1. Read problem, figure out what it’s asking for, and let represent one of the unknown quantities.

ex: Let be the smaller number.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

1. Read problem, figure out what it’s asking for, and let represent one of the unknown quantities.

ex: Let be the smaller number.

2. Write expressions for other unknown quantities.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

1. Read problem, figure out what it’s asking for, and let represent one of the unknown quantities.

ex: Let be the smaller number.

2. Write expressions for other unknown quantities.

ex: The larger number is .

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

3. Write equation in based on some part of the problem.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

3. Write equation in based on some part of the problem.

ex:

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

3. Write equation in based on some part of the problem.

ex:

4. Solve equation, and answer problem.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

3. Write equation in based on some part of the problem.

ex:

4. Solve equation, and answer problem.

ex: . So, the numbers are 4 and 6.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

3. Write equation in based on some part of the problem.

ex:

4. Solve equation, and answer problem.

ex: . So, the numbers are 4 and 6.

5. Check solution.

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Ex 1.A number is two more than another number. The sum of the numbers is 10. What are the two numbers?

3. Write equation in based on some part of the problem.

ex:

4. Solve equation, and answer problem.

ex: . So, the numbers are 4 and 6.

5. Check solution.

ex: Indeed, 6 is two more than 4, and .

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Ex 2.You are choosing between two pay-as-you-go cell phone plans. The one from Me-Tobile is $15 plus $0.08 per minute, and the one from Revison is $3 plus $0.12 per minute. After how many minutes of usage do the cell phone plans cost the same?

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Ex 3.You buy a Math 71 textbook with a 30% discount for $87.50. What was the book’s price before the discount?

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Ex 4.The length of an American football field is 200 feet more than the width. If the perimeter of the field is 1040 feet, what are its dimensions? (Hint: )

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Sometimes, we’ll want to rewrite a formula (like ) so it’s solved for a different variable (like ).

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Sometimes, we’ll want to rewrite a formula (like ) so it’s solved for a different variable (like ).

Ex 5.Solve the formula for .

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Ex 6.Solve the formula for .

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Ex 7.Solve the formula for .