Question

I need help figuring this out. PLEASE HELP!!
Find 2r squared + 3s cubed - r squared + 4t squared - r squared if r = -2, s = -3, and t = 5.
I thought I had it and no matter how I switch it around I always get an answer that isn't even close in range with the ones given.
A. -19
B. -37
C. 27
D. 19

I'm not just asking this for the answer but How exactly I am supposed to answer it, so that way I can answers ones like this in the future. Thanks.

Answer 1

Is the answer 19?

Answer 2

I wish I knew.

Answer 3

Ah, ok. I have got it 19 and maybe you'll have to trust it. See, the eqn comes out like:
\[2r ^{2} +3s ^{3} - r ^{2} + 4t ^{2} -r ^{2}\]
The r's get cancelled. Put the values of s and t and it comes, acc to me, 100-81 which is 19.

Answer 4

Ohh, okay, yes. I see it now. I complete forgot about how the r's would get cancelled out. Thank you so much.

Answer 5

Pleasure. Can you help me with something? How can I change this profile picture? :P

Answer 6

When you go into your settings, there should be your empty icon in the left corner and it says change picture in blue next to it.

Answer 7

When you go into your settings, there should be your empty icon in the left corner and it says change picture in blue next to it.

Answer 8

Thank you!