Question

another adding and subtracting polynomials question i'm having trouble with: ([a^3]-[2a^2])-([3a^2]-[4a^3]) my answer was (-3a^3)+(-1a^2) can anybody tell me where i went wrong?

Answer 1

you have
\[(a^3 -2a^2) -(3a^2 -4a^3) \]

the minus sign in front of \( (3a^2 -4a^3) \) means we subtract each thing inside the parens
so the problem is the same as
\[ a^3 -2a^2-3a^2 - -4a^3\]

Answer 2

@phi thanks :)

Answer 3

we are not done yet.
first, remember "minus a minus is a plus"
so you can change - -4a^3 to +4a^3
and you can change
\[ a^3 -2a^2-3a^2 - -4a^3 \]
to
\[ a^3 -2a^2-3a^2 + 4a^3 \]

Answer 4

in
\[ a^3 -2a^2-3a^2 + 4a^3 \]
you have 1 a^3 (one "a cubed") plus another 4 a^3 (another 4 of "a cubed")
how many a^3 do you have ?