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More on Solving Equations

More on Solving Equations. Section 4. 7x + x – 2x + 9 = 15. Answer: 7x + x – 2x + 9 = 15 6x + 9 = 15 -9 -9 ___________ 6x = 6 x = 1. Solve:. Grouping Symbols……. You might have to distribute before you combine like terms. 2(x + 3) = x + 7. Answer:

margaret-johnston
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More on Solving Equations

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  1. More on Solving Equations Section 4

  2. 7x + x – 2x + 9 = 15 Answer: 7x + x – 2x + 9 = 15 6x + 9 = 15 -9 -9 ___________ 6x = 6 x = 1 Solve:

  3. Grouping Symbols…… • You might have to distribute before you combine like terms.

  4. 2(x + 3) = x + 7 Answer: 2(x + 3) = x + 7 2x + 6 = x + 7 -x -x ____________ x + 6 = 7 -6 -6 _____________ x = 1 Solve:

  5. 2(2x + 3) = 18 Answer: 2(2x + 3) = 18 4x + 6 = 18 -6 -6 ____________ 4x = 12 x = 3 Solve:

  6. 4(2x) + 5 – 3x = x + 13 Answer: 4(2x) + 5 – 3x = x + 13 8x + 5 – 3x = x + 13 5x + 5 = x + 13 -x -x ________________ 4x + 5 = 13 -5 -5 ________________ 4x = 8 x = 2 Solve

  7. 2(x+5)= 3(x + 2) + x Answer: 2x + 10 = 3(x + 2) + x 2x + 10 = 3x + 6 + x 2x + 10 = 4x + 6 -4x -4x __________________ -2x + 10 = 6 -10 -10 __________________ -2x = -4 x = 2 Solve:

  8. 2(3x + 2) = 2(x+8) Answer: 2(3x + 2) = 2x + 16 6x + 4 = 2x + 16 -2x -2x ________________ 4x + 4 = 16 -4 -4 _________________ 4x = 12 x = 3 Solve:

  9. Word Problems Section 5

  10. Words that tell you to add…. • Plus • Increased By • Sum • More Than

  11. Words that tell you to subtract… • Minus • Decreased By • Difference • Less Than

  12. Multiply – Product times Divide – Quotient Ratio of Multiply and Divide Words…..

  13. 9 increased by 2 5 decreased by m Sum of 4 and 2x 7 less than 12 7 increased by 5 times a number 8 decreased by 3 times a number The sum of twice a number and 5 9 + 2 5 – m 4 + 2x 12 – 7 7 + 5n 8 – 3x 2y + 5 Write the mathematical statement for the following…..

  14. The sum of 7 and 3 times a number 4 times Harry’s age increased by 2 8 pounds less than twice wanda’s weight 7 + 3n 4h + 2 2w - 8 You Try…..

  15. The $500 selling price of a TV is $70 less than 3 times the cost. Find the profit Let’s define the variables first: Let C = Cost Let P = Profit Let SP = Selling Price Word Problems……

  16. The $500 selling price of a TV is $70 less than 3 times the cost.Find the profit. • Think: Cost + Profit = Selling Price C + P = SP • We know the selling price and are looking for the profit. Somehow we need to find the cost first: • 3C – 70 = $500 3C = $570 Cost = $190. We are still looking for the profit.

  17. The $500 selling price of a TV is $70 less than 3 times the cost.Find the profit. • We know that the cost = 190. • Cost + Profit = Selling Price. • 190 + P = 500 P = 500 – 190 Profit = $310 (This is the answer)

  18. You Try…… • The $140 selling price of a game is $60 less than twice the cost. • Find the profit.

  19. 1st find the cost: 2C – 60 = 140 2C = 140 + 60 2C = 200 C = $100 2nd find the profit: C + P = SP 100 + P = 140 P = 140 – 100 Profit = $40 The $140 selling price of a game is $60 less than twice the cost. Find the profit.

  20. Example…… • Mr. Daniel’s family rented a car when they flew to Hawaii for a 3-day vacation. They paid $42 per day and $0.07 for each mile driven. How much did it cost to rent the car for 3 days and drive 200 miles?

  21. Mr. Daniel’s family rented a car when they flew to Hawaii for a 3-day vacation. They paid $42 per day and $0.07 for each mile driven. How much did it cost to rent the car for 3 days and drive 200 miles? Total Cost = (Cost Per Day)(# of Days) + (Cost Per Mile)(# of Miles) Cost = (42)(3) + (200)(0.07) Cost = $126 + $14 Cost = $140 Answer…..

  22. Example…… • A car repair shop charged Mr. Jacobs $96 for an automotive part plus $72 per hour that a mechanic worked to install the part. The total charge was $388. For about how long did the mechanic work to install the part on Mr. Jacob’s car?

  23. A car repair shop charged Mr. Jacobs $96 for an automotive part plus $72 per hour that a mechanic worked to install the part. The total charge was $388. For about how long did the mechanic work to install the part on Mr. Jacob’s car? Total Cost = Base fee + (Charge Per Hour)(# of hours) $388 = $96 + $72(hours) 388 = 96 + 72H 388 – 96 = 72H 292 = 72H H = 4.06 or 4 Hours Answer……

  24. Example…… • The length of a rectangle is 5 and the area is 35. Find the perimeter of the rectangle.

  25. The length of a rectangle is 5 and the area is 35. Find the perimeter of the rectangle. 1st: Find the width by using the area formula of a rectangle. A = length x width 35 = 5 x width width = 7 Answer……

  26. The length of a rectangle is 5 and the area is 35. Find the perimeter of the rectangle. 2nd: Plug into the formula to find the perimeter. P = 2l + 2w P = 2(5) + 2(7) P = 10 + 14 P = 24 Remember the width = 7….

  27. Example…… • The perimeter of a rectangle is 20 and the width is 4. Find the area of the rectangle.

  28. The perimeter of a rectangle is 20 and the width is 4. Find the area of the rectangle. 1st: Find the length using the perimeter formula. P = 2w + 2l 20 = 2(4) + 2l 20 = 8 + 2l 12 = 2l l = 6 Answer…..

  29. The perimeter of a rectangle is 20 and the width is 4. Find the area of the rectangle. 2nd: Find the area. A = l x w A = 6 x 4 A = 24 Remember the length = 6…..

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