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26 votes
7(-a-3)=3(2a-6) I have the answer but I need help checking it.

User Ken Struys
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1 Answer

24 votes
24 votes

SOLUTION:

Step 1:

In this question, we are meant to solve the following:


7\text{ ( - a - 3 ) = 3 ( 2a - 6 )}

Step 2:

Simplifying, we have that:


\begin{gathered} -7a\text{ - 21 = 6a - 18} \\ \end{gathered}

collecting like terms, we have that:


\begin{gathered} -21\text{ + 18 = 6 a + 7a} \\ 13\text{ a = -3} \\ \text{Divide both sides by 13, we have that:} \\ a\text{ = }(-3)/(13) \end{gathered}

Step 3:

To verify that:


a\text{ =}(-3)/(13)

is a solution, we have that:


7\text{ ( - a - 3 ) = 7 \lbrack -(}(-3)/(13)\text{ ) - 3 \rbrack}
7\lbrack\text{ }(3)/(13)\text{ - 3\rbrack = 7 \lbrack }(3)/(13)\text{ - }(39)/(13)\text{ \rbrack = 7 x }(-36)/(13)\text{ = }(-252)/(13)\text{ ( Left Hand Side)}

Next,


3\text{ ( 2 a - 6 ) = 3 \lbrack{}2(}(-3)/(13))\text{ - 6 }\rbrack\text{ = 3 \lbrack}(-6)/(13)\text{ - 6\rbrack= 3\lbrack}(-6)/(13)\text{ - }(78)/(13)\rbrack
=\text{ 3 \lbrack }(-84)/(13)\text{ \rbrack = }(-252)/(13)\text{ ( Right Hand Side)}

CONCLUSION:

From the solution and from the verification of the answers, we can see that the correct answer is:


a\text{ = }\frac{-\text{ 3}}{13}

User Jeffery Grajkowski
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