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 If x=3, y=-2, z=-1 how would this problem be calculated?

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Problem: 2x - y2 + 3z3

 

I try doing it like this:

2x = 2·3 = 6

-y2 = -2·2 = -4

+3z3 = 3·-1·3 = -9

= 6-4-9 = -7; however, the answer to the equation (back of the book) tells me it is supposed to be -1?

Can you help me? If possible, also with step by step calculation?

 

-Much obliged :)

 Nov 5, 2015

Best Answer 

 #1
avatar+130536 
+15

2x - y2 + 3z3    ......x = 3, y = -2 and z = -1

 

2(3) - (-2)2 + 3(-1)3  =        [remember that (-2)2  is positive, but the negative out front makes it negative.....  and that (-1)3  = -1  .....so 3 * - 1  = -3]

 

6  - 4 - 3   =

 

6 - 7  =

 

-1

 

 

cool cool cool

 Nov 5, 2015
edited by CPhill  Nov 5, 2015

2+0 Answers

 #1
avatar+130536 
+15
Best Answer

2x - y2 + 3z3    ......x = 3, y = -2 and z = -1

 

2(3) - (-2)2 + 3(-1)3  =        [remember that (-2)2  is positive, but the negative out front makes it negative.....  and that (-1)3  = -1  .....so 3 * - 1  = -3]

 

6  - 4 - 3   =

 

6 - 7  =

 

-1

 

 

cool cool cool

CPhill Nov 5, 2015
edited by CPhill  Nov 5, 2015
 #2
avatar
+5

Sweet! That was really simple!

Thanks a lot :D

 Nov 5, 2015

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