Question

Choose the correct simplification of (2x3 + x2 − 4x) − (9x3 − 3x2).

11x3 − 2x2 − 4x
−7x3 + 4x2 − 4x
−2x3 − 2x2 − 4x
−7x3 − 4x2 − 4x

Answer 1

(2x^3 + x^2 − 4x) − (9x^3 − 3x^2).

Answer 2

Write it in a way that relates to elementary subtraction, it'll help more often than not (for me it does atleast)

What's 2-9?

Answer 3

\[(2x^3+x^2-4x)-(9x^3-3x^2)\]

Answer 4

Let's do it this way instead;

Which numbers have a x^3 with it?

Answer 5

9 @FortyTheRapper

Answer 6

There's one more number that has a x^3 next to it

Answer 7

2 @FortyTheRapper

Answer 8

You are subtracting a polynomial from a polynomial.

\(\large (2x^3 + x^2 − 4x) − (9x^3 − 3x^2) \)

First, write it without parentheses.
To remove parentheses, do this:
The first set of parentheses is not necessary, so just remove them.

\(\large = 2x^3 + x^2 − 4x − (9x^3 − 3x^2) \)

To remove the second set of parentheses, think of the negative sign outside the parentheses to the left to be a -1 multiplying the parentheses, and distribute the -1.

\(\large = 2x^3 + x^2 − 4x −1(9x^3 − 3x^2) \)

\(\large = 2x^3 + x^2 − 4x − 9x^3 + 3x^2 \)

Notice what happened when the parentheses were removed. All the signs inside became the opposite. That is what happens when you have a negative to the left of a set of parentheses.

Now you need to combine like terms. Like terms have the same variables with the same exponents. They can be added and subtracted.

Answer 9

B

Answer 10

thx

Answer 11

\(\large = 2x^3 + x^2 − 4x − 9x^3 + 3x^2\)

\(\large = -7x^3 + 4x^2 − 4x \)

Answer 12

B is correct.