Activity 1: We Co-Operate

a) Let [tex]f[/tex] and [tex]g[/tex] be defined as [tex]f(x) = x - 5[/tex] and [tex]g(x) = x^2 - 1[/tex]. Find:

1. [tex]f + g[/tex]
2. [tex]f - g[/tex]
3. [tex]f \cdot g[/tex]
4. [tex]\frac{f}{g}[/tex]
5. [tex]\frac{g}{g}[/tex]



Answer :

Certainly! Let's define the functions [tex]\( f \)[/tex] and [tex]\( g \)[/tex]:

[tex]\[ f(x) = x - 5 \][/tex]
[tex]\[ g(x) = x^2 - 1 \][/tex]

We will find the following expressions step-by-step using an arbitrary value [tex]\( x = 2 \)[/tex]:

1. [tex]\( f + g \)[/tex]:

[tex]\[ (f + g)(x) = f(x) + g(x) \][/tex]
Given [tex]\( x = 2 \)[/tex]:

[tex]\[ f(2) = 2 - 5 = -3 \][/tex]

[tex]\[ g(2) = 2^2 - 1 = 4 - 1 = 3 \][/tex]

[tex]\[ (f + g)(2) = f(2) + g(2) = -3 + 3 = 0 \][/tex]

Therefore, [tex]\( (f + g)(2) = 0 \)[/tex].

2. [tex]\( f - g \)[/tex]:

[tex]\[ (f - g)(x) = f(x) - g(x) \][/tex]
Given [tex]\( x = 2 \)[/tex]:

[tex]\[ f(2) = -3 \][/tex]

[tex]\[ g(2) = 3 \][/tex]

[tex]\[ (f - g)(2) = f(2) - g(2) = -3 - 3 = -6 \][/tex]

Therefore, [tex]\( (f - g)(2) = -6 \)[/tex].

3. [tex]\( f \cdot g \)[/tex]:

[tex]\[ (f \cdot g)(x) = f(x) \cdot g(x) \][/tex]
Given [tex]\( x = 2 \)[/tex]:

[tex]\[ f(2) = -3 \][/tex]

[tex]\[ g(2) = 3 \][/tex]

[tex]\[ (f \cdot g)(2) = f(2) \cdot g(2) = -3 \cdot 3 = -9 \][/tex]

Therefore, [tex]\( (f \cdot g)(2) = -9 \)[/tex].

4. [tex]\( \frac{f}{g} \)[/tex]:

[tex]\[ \left(\frac{f}{g}\right)(x) = \frac{f(x)}{g(x)} \][/tex]
Given [tex]\( x = 2 \)[/tex]:

[tex]\[ f(2) = -3 \][/tex]

[tex]\[ g(2) = 3 \][/tex]

[tex]\[ \left(\frac{f}{g}\right)(2) = \frac{f(2)}{g(2)} = \frac{-3}{3} = -1.0 \][/tex]

Therefore, [tex]\( \frac{f}{g}(2) = -1.0 \)[/tex].

5. [tex]\( \frac{g}{g} \)[/tex]:

[tex]\[ \left(\frac{g}{g}\right)(x) = \frac{g(x)}{g(x)} \][/tex]
Given [tex]\( x = 2 \)[/tex]:

[tex]\[ g(2) = 3 \][/tex]

[tex]\[ \left(\frac{g}{g}\right)(2) = \frac{g(2)}{g(2)} = \frac{3}{3} = 1.0 \][/tex]

Therefore, [tex]\( \frac{g}{g}(2) = 1.0 \)[/tex].

To summarize, when [tex]\( x = 2 \)[/tex]:

[tex]\[ \begin{align*} (f + g)(2) &= 0 \\ (f - g)(2) &= -6 \\ (f \cdot g)(2) &= -9 \\ \left(\frac{f}{g}\right)(2) &= -1.0 \\ \left(\frac{g}{g}\right)(2) &= 1.0 \\ \end{align*} \][/tex]