objective i will use the order of operations and rounding to find the exact and approximate...
DESCRIPTION
Rounding for the Final Answer Solve 7x + 32 = 128. Round to the nearest hundredth. 7x + 32 = 128Original equation 7x = 96Subtract 32 from each side x = …Divide both sides by 7 x ≈ 13.71Round to nearest hundredth The solution is approximatelyTRANSCRIPT
OBJECTIVE
• I will use the order of operations and rounding to find the exact and approximate solutions of equations that contain decimals.
Rounding for a Practical AnswerSix people buy some food to take to the lake. The
total cost for the food is $33.45. If each person pays the same amount, how much does each person owe?
6x = 33.45 Original equationx = 5.575 Exact answerx ≈ 5.58 Round to the nearest centEach person owes $5.58. The exact answer is not
practical because you cannot have a fraction of a cent, but six times the rounded answer does not correspond to the cost of the food. It is one cent too much due to round-off error.
Rounding for the Final Answer
Solve 7x + 32 = 128. Round to the nearest hundredth.7x + 32 = 128 Original equation7x = 96 Subtract 32 from each sidex = 13.714… Divide both sides by 7x ≈ 13.71 Round to nearest hundredthThe solution is approximately 13.71.
Guided Practice
1. Solve -12x - 13 = 37. Round to the nearest hundredth.
Original Equation Involving Decimals
• Solve using same methods used to solve equations without a decimal.
Solve 2.14x + 3.81 = 0.53x + 14.96. Round to the nearest hundredth.
2.14x + 3.81 = 0.53x + 14.961.61x = 11.15x = 6.925…x ≈ 6.93
Guided Practice
1. Solve 7.82x - 3.14 = 4.66x + 2.71. Round your answer to the nearest hundredth.
Changing Decimal Coefficients to Integers
• Change decimals to integers for easier calculationSolve 2.3x + 6.2 = 1.5x + 9.8. Round to the nearest tenth.2.3x + 6.2 = 1.5x + 9.7 Original Equation23x + 62 = 15x + 97 Multiply both sides by 108x = 35 Combine like termsx = 4.625x ≈ 4.6
Guided Practice
Re-write the coefficients as integers and solve. Round to the nearest tenth.
1. 5.7 - 3.4x = 2.2x - 7.1
Using a Verbal Model
You are shopping for roses. The total tax is 10%. You have a total of $27.79 to spend. What is your price limit for the roses?
Total cost is price limit and tax based on price limit.
Using a Verbal Model
Cost of Roses + Cost of Tax = Price Limitx + 0.10x = 27.79 Substitute1.10x = 27.79 Combine like termsx = 25.263… Divide both sides by 1.10x ≈ 25.26 Round downYou have a limited amount of money to spend,
so you must round down to $25.26. If you round up, the tax and total cost will increase and you will be a penny short.
Guided Practice
You are shopping for a bracelet. The sales tax is 5%. You have a total of $125.40 to spend. What is your price limit for the bracelet?
Independent Practice
Round answers to the nearest hundredth.1. 3x + 5 = 202. 2.51x - 4.27 = 1.13x + 2.153. Change the decimal coefficients to
integers to solve.3.4x - 2.3 = 1.7x + 5.4