If [tex]$f(x)=4-x^2$[/tex] and [tex]$g(x)=6x$[/tex], which expression is equivalent to [tex][tex]$(g-f)(3)$[/tex][/tex]?

A. [tex]$6-3-(4+3)^2$[/tex]
B. [tex]$6-3-(4-3^2)$[/tex]
C. [tex][tex]$6(3)-4+3^2$[/tex][/tex]
D. [tex]$6(3)-4-3^2$[/tex]



Answer :

Let us explore the expressions and determine the one that matches the correct result for [tex]\((g - f)(3)\)[/tex] where [tex]\(f(x) = 4 - x^2\)[/tex] and [tex]\(g(x) = 6x\)[/tex].

First, we need to evaluate [tex]\(f(3)\)[/tex] and [tex]\(g(3)\)[/tex] separately:

1. Evaluating [tex]\(f(3)\)[/tex]:
[tex]\[ f(x) = 4 - x^2 \Rightarrow f(3) = 4 - 3^2 = 4 - 9 = -5 \][/tex]

2. Evaluating [tex]\(g(3)\)[/tex]:
[tex]\[ g(x) = 6x \Rightarrow g(3) = 6 \cdot 3 = 18 \][/tex]

Next, we need to find [tex]\((g - f)(3)\)[/tex]:
[tex]\[ (g-f)(3) = g(3) - f(3) = 18 - (-5) = 18 + 5 = 23 \][/tex]

Now, let's check each given expression to see which one correctly evaluates to [tex]\(23\)[/tex]:

- Expression 1: [tex]\(6 - 3 - (4+3)^2\)[/tex]
[tex]\[ 6 - 3 - (4+3)^2 = 6 - 3 - 7^2 = 6 - 3 - 49 = 3 - 49 = -46 \][/tex]
This does not match the required value of [tex]\(23\)[/tex].

- Expression 2: [tex]\(6 - 3 - \left(4 - 3^2\right)\)[/tex]
[tex]\[ 6 - 3 - \left(4 - 3^2\right) = 6 - 3 - (4 - 9) = 6 - 3 - (-5) = 6 - 3 + 5 = 3 + 5 = 8 \][/tex]
This does not match the required value of [tex]\(23\)[/tex].

- Expression 3: [tex]\(6(3) - 4 + 3^2\)[/tex]
[tex]\[ 6(3) - 4 + 3^2 = 18 - 4 + 9 = 18 - 4 + 9 = 14 + 9 = 23 \][/tex]
This matches the required value of [tex]\(23\)[/tex].

- Expression 4: [tex]\(6(3) - 4 - 3^2\)[/tex]
[tex]\[ 6(3) - 4 - 3^2 = 18 - 4 - 9 = 18 - 4 - 9 = 14 - 9 = 5 \][/tex]
This does not match the required value of [tex]\(23\)[/tex].

Therefore, the correct expression is:
[tex]\[ 6(3) - 4 + 3^2 \][/tex]

So, the equivalent expression to [tex]\((g - f)(3)\)[/tex] is:
[tex]\[ 6(3) - 4 + 3^2 \][/tex]