High School

What is the result of subtracting the polynomial [tex]\left(4x^3-2x^2+5\right)-\left(3x^3+x-4\right)[/tex]?

A. [tex]x^3-2x^2+9[/tex]
B. [tex]x^3-2x^2-x+9[/tex]
C. [tex]x^3-2x^2-x+1[/tex]
D. [tex]x^3+2x^2+9[/tex]

Answer :

We start with the expression

[tex]$$
\left(4 x^3 - 2 x^2 + 5\right) - \left(3 x^3 + x - 4\right).
$$[/tex]

Step 1: Remove Parentheses

When subtracting, it is important to distribute the negative sign to each term in the second polynomial. This gives:

[tex]$$
4x^3 - 2x^2 + 5 - 3x^3 - x + 4.
$$[/tex]

Step 2: Combine Like Terms

Group the terms with the same power of [tex]$x$[/tex]:

- Combine the [tex]$x^3$[/tex] terms:

[tex]$$
4x^3 - 3x^3 = x^3.
$$[/tex]

- The [tex]$x^2$[/tex] term remains as is:

[tex]$$
-2x^2.
$$[/tex]

- Combine the [tex]$x$[/tex] terms:

[tex]$$
-x.
$$[/tex]

- Combine the constant terms:

[tex]$$
5 + 4 = 9.
$$[/tex]

Step 3: Write the Result

Putting the combined terms together, the resulting polynomial is:

[tex]$$
x^3 - 2x^2 - x + 9.
$$[/tex]

Comparing this with the given options, we see that it matches option B:

[tex]$$
x^3 - 2x^2 - x + 9.
$$[/tex]

Thus, the final answer is option B.