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Math

Math Snap

PROBLEM

Suppose that the functions ss and tt are defined for all real numbers xx as follows.
s(x)=4xt(x)=3x1\begin{array}{l} s(x)=4 x \\ t(x)=3 x-1 \end{array} Write the expressions for (st)(x)(s \cdot t)(x) and (s+t)(x)(s+t)(x) and evaluate (st)(2)(s-t)(-2).
(st)(x)=(s+t)(x)=(st)(2)=\begin{array}{r} (s \cdot t)(x)= \\ (s+t)(x)= \\ (s-t)(-2)= \end{array} \square
\square
\square

STEP 1

1. We are given the functions s(x)=4x s(x) = 4x and t(x)=3x1 t(x) = 3x - 1 .
2. We need to find expressions for (st)(x) (s \cdot t)(x) and (s+t)(x) (s + t)(x) .
3. We need to evaluate (st)(2) (s - t)(-2) .

STEP 2

1. Find the expression for (st)(x) (s \cdot t)(x) .
2. Find the expression for (s+t)(x) (s + t)(x) .
3. Evaluate (st)(2) (s - t)(-2) .

STEP 3

To find (st)(x) (s \cdot t)(x) , multiply the functions s(x) s(x) and t(x) t(x) :
(st)(x)=s(x)t(x)=(4x)(3x1) (s \cdot t)(x) = s(x) \cdot t(x) = (4x) \cdot (3x - 1)

STEP 4

Distribute to simplify the expression:
(st)(x)=4x3x4x1 (s \cdot t)(x) = 4x \cdot 3x - 4x \cdot 1 (st)(x)=12x24x (s \cdot t)(x) = 12x^2 - 4x

STEP 5

To find (s+t)(x) (s + t)(x) , add the functions s(x) s(x) and t(x) t(x) :
(s+t)(x)=s(x)+t(x)=4x+(3x1) (s + t)(x) = s(x) + t(x) = 4x + (3x - 1)

STEP 6

Simplify the expression:
(s+t)(x)=4x+3x1 (s + t)(x) = 4x + 3x - 1 (s+t)(x)=7x1 (s + t)(x) = 7x - 1

STEP 7

To evaluate (st)(2) (s - t)(-2) , first find the expression for (st)(x) (s - t)(x) :
(st)(x)=s(x)t(x)=4x(3x1) (s - t)(x) = s(x) - t(x) = 4x - (3x - 1)

STEP 8

Simplify the expression:
(st)(x)=4x3x+1 (s - t)(x) = 4x - 3x + 1 (st)(x)=x+1 (s - t)(x) = x + 1

SOLUTION

Substitute x=2 x = -2 into (st)(x) (s - t)(x) :
(st)(2)=(2)+1 (s - t)(-2) = (-2) + 1 (st)(2)=1 (s - t)(-2) = -1 The expressions and evaluation are:
(st)(x)=12x24x(s+t)(x)=7x1(st)(2)=1\begin{array}{r} (s \cdot t)(x) = 12x^2 - 4x \\ (s + t)(x) = 7x - 1 \\ (s - t)(-2) = -1 \end{array}

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