Question

I keep on re-doing this problem and getting different answers. Help?

Evaluate the expression: x^2-81-px+40 given x=2, p=5.
So, 2^2-81-(5)(2)+40

My most recent answers are -27 & -48, but I've also gotten 164, -46, 106, and -124.

Answer 1

.....
2^2-81-(5)(2)+40
4 -81 -10+40

44-91

-47

Answer 2

E none of the above

Answer 3

my suggestion to you, write it down and take it step by step

and when in doubt, grab a calculator if you keep making a mistake when adding and subtracting to check your answer as i am assuming that is where you made your mistake

on a side note, do not rely on a calculator

Answer 4

wow my grammar was off there
too many thoughts jumbled up in my head

use a calculator to check your answer
use it as a last resort

Answer 5

Ok, so I was able to follow along and actually got -47, but you lost me on how you were able to get 44-91. The way I ended up doing it was:

4-81-10+40
-77-10+40
-87+40
= -47

Can you tell me how you were able to get 44-91?

Answer 6

using the commutative property of addition

4-81-10+40 = 4+40 - 81 - 10

(4+40) (- 81 - 10)
44 - 91

Answer 7

I had absolutely no idea you could do that. Wow. Okay, I think I get everything now. Thanks a lot!

Answer 8

commutative property of addition means you can add and subtract in any order

Answer 9

a+ b = b+ a

Answer 10

unless there is a parenthesis seperating it

in which case you would need to follow order of operation
otherwise known as PEMDAS

Answer 11

Oh, I see. Seriously, thanks so much. I'm going to have to brush up on the properties of addition. Thanks a lot for the tip about parentheses, too. I seriously had no idea you could solve this type of problem that way.

Answer 12

definitely look up order of operations

Answer 13

Will do. Once again, thanks a lot. You were extremely helpful.

Answer 14

no problem