High School

Multiply the following expression:

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

Choose the correct option:

A. [tex]2x^4-9x^3-9x^2-15x[/tex]

B. [tex]4x^4+9x^3-8x^2+15x[/tex]

C. [tex]2x^4-9x^3-8x^2+15x[/tex]

D. [tex]2x^4+9x^3-8x^2+15x[/tex]

Answer :

To multiply the polynomials
[tex]$$\left(x^2-5x\right)\left(2x^2+x-3\right),$$[/tex]
we start by using the distributive property.

1. Multiply each term in the first polynomial by each term in the second polynomial.

  Multiply [tex]$x^2$[/tex] by each term in [tex]$(2x^2 + x -3)$[/tex]:
  [tex]$$x^2 \cdot 2x^2 = 2x^4,$$[/tex]
  [tex]$$x^2 \cdot x = x^3,$$[/tex]
  [tex]$$x^2 \cdot (-3) = -3x^2.$$[/tex]

  So, the first group of terms is:
  [tex]$$2x^4 + x^3 - 3x^2.$$[/tex]

2. Next, multiply [tex]$-5x$[/tex] by each term in [tex]$(2x^2 + x -3)$[/tex]:
  [tex]$$-5x \cdot 2x^2 = -10x^3,$$[/tex]
  [tex]$$-5x \cdot x = -5x^2,$$[/tex]
  [tex]$$-5x \cdot (-3) = 15x.$$[/tex]

  So, the second group of terms is:
  [tex]$$-10x^3 - 5x^2 + 15x.$$[/tex]

3. Now, add the two results together:
[tex]$$\begin{align*}
(2x^4 + x^3 - 3x^2) + (-10x^3 - 5x^2 + 15x) &= 2x^4 + (x^3 - 10x^3) + (-3x^2 - 5x^2) + 15x \\
&= 2x^4 - 9x^3 - 8x^2 + 15x.
\end{align*}$$[/tex]

Thus, the final expanded expression is
[tex]$$2x^4 - 9x^3 - 8x^2 + 15x.$$[/tex]

The correct answer is Option C.