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Arithmetic Operations on Functions

Given that [tex]f(x) = x^2 + 4x - 21[/tex] and [tex]g(x) = x - 3[/tex], find [tex](f \div g)(x)[/tex] and express the result in standard form.

Answer:

[tex]\square$

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Sagot :

To solve the given problem, we need to find [tex]\((f \div g)(x)\)[/tex], which means dividing the function [tex]\( f(x) \)[/tex] by the function [tex]\( g(x) \)[/tex].

Given the functions:
[tex]\[ f(x) = x^2 + 4x - 21 \][/tex]
[tex]\[ g(x) = x - 3 \][/tex]

We need to determine:
[tex]\[ \left( \frac{f}{g} \right)(x) \][/tex]

Follow these steps:

1. Set Up the Division:
We need to divide [tex]\( f(x) \)[/tex] by [tex]\( g(x) \)[/tex]:
[tex]\[ \left( \frac{x^2 + 4x - 21}{x - 3} \right) \][/tex]

2. Perform Polynomial Division:
To simplify the expression, divide [tex]\( x^2 + 4x - 21 \)[/tex] by [tex]\( x - 3 \)[/tex]:

- First Term:
Divide the leading term of the numerator [tex]\( x^2 \)[/tex] by the leading term of the denominator [tex]\( x \)[/tex]:
[tex]\[ \frac{x^2}{x} = x \][/tex]
Multiply [tex]\( x \)[/tex] by the entire denominator [tex]\( x - 3 \)[/tex]:
[tex]\[ x \cdot (x - 3) = x^2 - 3x \][/tex]
Subtract this product from the original numerator:
[tex]\[ (x^2 + 4x - 21) - (x^2 - 3x) = 4x - 3x - 21 = 7x - 21 \][/tex]

- Second Term:
Divide the new leading term [tex]\( 7x \)[/tex] by [tex]\( x \)[/tex]:
[tex]\[ \frac{7x}{x} = 7 \][/tex]
Multiply [tex]\( 7 \)[/tex] by the denominator [tex]\( x - 3 \)[/tex]:
[tex]\[ 7 \cdot (x - 3) = 7x - 21 \][/tex]
Subtract this product from the new remainder:
[tex]\[ (7x - 21) - (7x - 21) = 0 \][/tex]

3. Combine the Quotients:
The division gives us:
[tex]\[ x + 7 \][/tex]
Thus, we rewrite the original fraction:
[tex]\[ \frac{x^2 + 4x - 21}{x - 3} = x + 7 \][/tex]

4. Express in Standard Form:
Finally, we express the result of [tex]\((f \div g)(x)\)[/tex] in a standard algebraic form:
[tex]\[ \left( \frac{f}{g} \right)(x) = x + 7 + \frac{0}{x - 3} \][/tex]

Summarizing the entire division and steps, we obtain:
[tex]\[ \left( \frac{f}{g} \right)(x) = x + 7 \][/tex]

And therefore, the final answer is:
[tex]\[ \boxed{x + 7} \][/tex]