SOLUTION: Which of the expressions is not equal to the other three? A. 7[a +2] B. 20 + 8a -6 -a C.17 +3[a -1] + 4a D. 2a + 5[a -1] + 8

Algebra ->  Test -> SOLUTION: Which of the expressions is not equal to the other three? A. 7[a +2] B. 20 + 8a -6 -a C.17 +3[a -1] + 4a D. 2a + 5[a -1] + 8      Log On


   

Question 1207907: Which of the expressions is not equal to the other three?
A. 7[a +2]
B. 20 + 8a -6 -a
C.17 +3[a -1] + 4a
D. 2a + 5[a -1] + 8
Found 3 solutions by greenestamps, ikleyn, Edwin McCravy:
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Simplify each expression by combining like terms and/or using the distributive property to get rid of parentheses.

A. 7(a+2) = 7(a)+7(2) = 7a+14
B. 20+8a-6-a = (8a-a)+(20-6) = 7a+14
C. 17+3(a-1)+4a = 17+3(a)+3(-1)+4a = 17+3a-3+4a = (3a+4a)+(17-3)=7a+14
D. 2a+5(a-1)+8 = 2a+5(a)+5(-1)+8 = 2a+5a-5+8 = 7a+3

ANSWER: D

Answer by ikleyn(52786) About Me  (Show Source):
You can put this solution on YOUR website!
.
Which of the expressions is not equal to the other three?
A. 7[a +2]
B. 20 + 8a -6 -a
C.17 +3[a -1] + 4a
D. 2a + 5[a -1] + 8
~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

One way to solve this problem is to simplify each expression to its simplest form
and compare them.


I will use another way. I will quickly calculate in my head the value of each expression for a = 0.


(A)  gives the value of 14.

(B)  gives the value of 14.

(C)  gives the value of 14.

(D)  gives the value of  3.


So, I conclude that expression (D) is not equal to (is different from) other three.

Solved.



Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
That sort of thing saves lots of time on such questions on exams.  If
substituting 0 gives the same results on some answers, substitute 1 or -1.

Edwin