Suppose that the functions [tex] s [/tex] and [tex] t [/tex] are defined for all real numbers [tex] x [/tex] as follows:

[tex]\[
\begin{array}{l}
s(x) = 4x - 5 \\
t(x) = x - 4
\end{array}
\][/tex]

Write the expressions for [tex] (s - t)(x) [/tex] and [tex] (s \cdot t)(x) [/tex] and evaluate [tex] (s + t)(-1) [/tex]:

[tex]\[
\begin{array}{l}
(s - t)(x) = \square \\
(s \cdot t)(x) = \square \\
(s + t)(-1) = \square
\end{array}
\][/tex]



Answer :

Sure! Let's go through each part of the problem step-by-step.

1. Finding [tex]\((s - t)(x)\)[/tex]:
[tex]\[ s(x) = 4x - 5 \][/tex]
[tex]\[ t(x) = x - 4 \][/tex]

Now, we calculate [tex]\((s - t)(x)\)[/tex]:
[tex]\[ (s - t)(x) = s(x) - t(x) = (4x - 5) - (x - 4) \][/tex]
Simplify the expression:
[tex]\[ (s - t)(x) = 4x - 5 - x + 4 = 3x - 1 \][/tex]
Therefore,
[tex]\[ (s - t)(x) = 3x - 1 \][/tex]

2. Finding [tex]\((s \cdot t)(x)\)[/tex]:
[tex]\[ s(x) = 4x - 5 \][/tex]
[tex]\[ t(x) = x - 4 \][/tex]

Now, we calculate [tex]\((s \cdot t)(x)\)[/tex]:
[tex]\[ (s \cdot t)(x) = s(x) \cdot t(x) = (4x - 5) \cdot (x - 4) \][/tex]
Expand the expression:
[tex]\[ (s \cdot t)(x) = 4x(x - 4) - 5(x - 4) \][/tex]
[tex]\[ (s \cdot t)(x) = 4x^2 - 16x - 5x + 20 \][/tex]
Simplify the expression:
[tex]\[ (s \cdot t)(x) = 4x^2 - 21x + 20 \][/tex]
Therefore,
[tex]\[ (s \cdot t)(x) = 4x^2 - 21x + 20 \][/tex]

3. Evaluating [tex]\((s + t)(-1)\)[/tex]:
[tex]\[ s(x) = 4x - 5 \][/tex]
[tex]\[ t(x) = x - 4 \][/tex]

First, we need to find [tex]\(s(-1)\)[/tex] and [tex]\(t(-1)\)[/tex]:
[tex]\[ s(-1) = 4(-1) - 5 = -4 - 5 = -9 \][/tex]
[tex]\[ t(-1) = -1 - 4 = -5 \][/tex]

Now, we calculate [tex]\((s + t)(-1)\)[/tex]:
[tex]\[ (s + t)(-1) = s(-1) + t(-1) = -9 + (-5) = -14 \][/tex]
Therefore,
[tex]\[ (s + t)(-1) = -14 \][/tex]

To summarize:
[tex]\[ \begin{array}{l} (s - t)(x) = 3x - 1 \\ (s \cdot t)(x) = 4x^2 - 21x + 20 \\ (s + t)(-1) = -14 \end{array} \][/tex]