Question

Which expression is equivalent to (4c - 9)(c2 + c - 7)?

A) 4c3 + 63
B) 4c3 - 5c2 - 37c + 63
C) 4c3 + 4c2 - 28c - 63
D) 4c3 - 33c2 - 9c - 63

Can someone also explain how? I dont understand the steps...

Answer 1

the easiest way would be to draw a box 3x2, or 2x3 (doesn't matter). then put the different terms there, cross multiply them and collect/simplify all the terms

Answer 2

hold on I'll draw it so it's easy to see

Answer 3

so then you multiply them and write it in the smaller boxes. For example the top left box would be 4c^3.

Do it for all of the boxes and combine like terms, simplify to get your final answer

Answer 4

I'm not sure i understand, so like in the first box it would be 4c^2, second 4c(c) and third 4c(-7)? Is there another way besides the box method? :/

Answer 5

(4c - 9)(c2 + c - 7)?

4c(c2+c-7) -9 ( c2+c-7)

4c3+4c2-28c-9c2-9c+63

4c3-5c2-37c+63

Answer 6

just do it the way i did. no need to make boxes and indulge yourself in complications this is basic algebra. good luck!

Answer 7

the box is basically a way to keep track of your work. It's basically the same as what @hashsam1 does but it helps visualize if you're not familiar with it i guess.

And yea you're doing right, except for the first one it's 4c^3 (it's c squared times 4c so it's 4c cubed)

Answer 8

so continue doing the bottom row, then add all the like terms. hopefully you'll get what hashsam1 got