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If [tex]$p(x)=2x^2 - 4x$[/tex] and [tex]$q(x)=x - 3$[/tex], what is [tex][tex]$(p \circ q)(x)$[/tex][/tex]?

A. [tex]$2x^2 - 4x + 12$[/tex]

B. [tex]$2x^2 - 16x + 18$[/tex]

C. [tex][tex]$2x^2 - 16x + 30$[/tex][/tex]

D. [tex]$2x^2 - 16x + 15$[/tex]


Sagot :

To solve for [tex]\( (p \circ q)(x) \)[/tex]:

First, we need to understand what [tex]\( (p \circ q)(x) \)[/tex] means. It represents the composition of the two functions [tex]\( p(x) \)[/tex] and [tex]\( q(x) \)[/tex], so we substitute [tex]\( q(x) \)[/tex] into [tex]\( p(x) \)[/tex].

Given the functions:
[tex]\[ p(x) = 2x^2 - 4x \][/tex]
[tex]\[ q(x) = x - 3 \][/tex]

The composition [tex]\( (p \circ q)(x) \)[/tex] is defined as [tex]\( p(q(x)) \)[/tex]. So, we substitute [tex]\( q(x) \)[/tex] into [tex]\( p(x) \)[/tex]:

1. Substitute [tex]\( q(x) = x - 3 \)[/tex] into [tex]\( p(x) \)[/tex]:
[tex]\[ p(q(x)) = p(x-3) \][/tex]

2. Now, replace [tex]\( x \)[/tex] in [tex]\( p(x) \)[/tex] with [tex]\( x-3 \)[/tex]:
[tex]\[ p(x-3) = 2(x-3)^2 - 4(x-3) \][/tex]

3. Simplify the expression:
[tex]\[ (x-3)^2 = x^2 - 6x + 9 \][/tex]
So,
[tex]\[ 2(x-3)^2 = 2(x^2 - 6x + 9) = 2x^2 - 12x + 18 \][/tex]
And,
[tex]\[ -4(x-3) = -4x + 12 \][/tex]

4. Combine these results:
[tex]\[ p(x-3) = 2x^2 - 12x + 18 - 4x + 12 \][/tex]
Simplifying further,
[tex]\[ p(x-3) = 2x^2 - 16x + 30 \][/tex]

Thus, [tex]\( (p \circ q)(x) = 2x^2 - 16x + 30 \)[/tex].

Therefore, the correct answer is:
[tex]\[ 2 x^2 - 16 x + 30 \][/tex]

So, the correct option is:
[tex]\[ 2 x^2 - 16 x + 30 \][/tex]