Question

Find the sum of 12a + 7b, −6a − 9, and 14a − 12b.

A) 20a - 5b - 9
B) 20a + 5b - 9
C) 20a - 5b + 9
D) 20a + 5b + 9

Answer 1

The answer is (A)

Step-by-step explanation:

(12a + 7b) + (−6a - 9) + (14a − 12b)

Hence,

20a - 5b - 9

Answer 2

The answer is: [A]: " 20a − 5b − 9 " .
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Step-by-step explanation:
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(12a + 7b) + (−6a − 9) + (14a − 12b) =

12a + 7b + 1(−6a − 9) + 1(14a − 12b) =

12a + 7b + (1*-6a) + (1*-9) + (1*14a) + (1* -12b) =

12a + 7b − 6a − 9 + 14a − 12b = ?

Combine the "like terms:

12a − 6a + 14a = 20a ;

7b − 12b = - 5b ;

and then we have "-9" ;
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So, write as: " 20a − 5b − 9 " ; which is: Answer choice: [A].
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