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Math - Find the Mistake

by Kelsea
(FL)










































Find the Mistake: Provided below is a solution to the equation 8x + 7 - 2x = 27 - 2. Choose the statement that is true about the given solution.
Line # 8x + 7 - 2x = 27 - 2
1 6x + 7 = 25
2 x + 7 = 19
3 x = 12

Comments for Math - Find the Mistake

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Dec 29, 2011
Find the Mistake
by: Staff


Question:

by Kelsea
(FL)

Find the Mistake: Provided below is a solution to the equation 8x + 7 - 2x = 27 - 2. Choose the statement that is true about the given solution.

Line # 8x + 7 - 2x = 27 - 2
1 6x + 7 = 25
2 x + 7 = 19
3 x = 12


Answer:


Line 1 is correct

6x + 7 = 25, correct


Lines 2 and 3 are incorrect

x + 7 = 19, incorrect

3 x = 12, incorrect



The correct solution is shown below:

8x + 7 - 2x = 27 - 2


Combine like terms on both the left and right side of the equation

8x + 7 - 2x = 27 - 2

8x + 7 - 2x = 25

8x - 2x + 7 = 25

6x + 7 = 25, this is the same as line 1 in the problem statement


Subtract 7 from each side of the equation. This eliminates the 7 on the left side of the equation.

6x + 7 = 25

6x + 7 - 7 = 25 - 7

6x + 0 = 25 - 7

6x = 25 - 7

6x = 18


Divide each side of the equation by 6. This eliminates the 6 on the left side of the equation.

6x/6 = 18/6

x*(6/6) = 18/6

x*(1) = 18/6

x = 18/6

x = 3

the correct answer: x = 3



check the answer: substitute 3 for every x in the original equation

8x + 7 - 2x = 27 - 2

8*3 + 7 - 2*3 = 27 - 2

24 + 7 - 6 = 27 - 2

25 = 27 - 2

25 = 25, OK → x = 3 is a VALID solution



Thanks for writing.


Staff
www.solving-math-problems.com


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