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Math

Math Snap

PROBLEM

Suppose that the functions gg and hh are defined for all real numbers xx as follows.
g(x)=4x2h(x)=x3\begin{array}{l} g(x)=4 x^{2} \\ h(x)=x^{3} \end{array} Write the expressions for (gh)(x)(g \cdot h)(x) and (gh)(x)(g-h)(x) and evaluate (g+h)(1)(g+h)(-1).
(gh)(x)=(gh)(x)=(g+h)(1)=\begin{array}{r} (g \cdot h)(x)=\square \\ (g-h)(x)=\square \\ (g+h)(-1)=\square \end{array}

STEP 1

What is this asking?
We're given two functions, g(x)g(x) and h(x)h(x), and we need to find the expressions for when they're multiplied and subtracted, and also figure out what happens when we add them and plug in x=1x = -1.
Watch out!
Don't mix up multiplying functions with multiplying regular numbers!
Also, remember that (1)2(-1)^2 is positive, but (1)3(-1)^3 is negative.

STEP 2

1. Find (gh)(x)(g \cdot h)(x)
2. Find (gh)(x)(g - h)(x)
3. Evaluate (g+h)(1)(g + h)(-1)

STEP 3

Alright, let's multiply those functions!
We're given g(x)=4x2g(x) = 4x^2 and h(x)=x3h(x) = x^3.
So, (gh)(x)(g \cdot h)(x) just means g(x)h(x)g(x) \cdot h(x).

STEP 4

Let's substitute the expressions for g(x)g(x) and h(x)h(x):
(gh)(x)=(4x2)(x3)(g \cdot h)(x) = (4x^2) \cdot (x^3)

STEP 5

Now, we multiply the coefficients and add the exponents of xx:
(gh)(x)=4x2+3=4x5(g \cdot h)(x) = 4x^{2+3} = 4x^5 So, (gh)(x)=4x5(g \cdot h)(x) = 4x^5!

STEP 6

Time to subtract! (gh)(x)(g - h)(x) means g(x)h(x)g(x) - h(x).

STEP 7

Let's substitute again:
(gh)(x)=(4x2)(x3)(g - h)(x) = (4x^2) - (x^3)

STEP 8

We can rewrite this as:
(gh)(x)=4x2x3(g - h)(x) = 4x^2 - x^3 That's it!
We can't simplify this any further.

STEP 9

Now, we're going to add the functions and then plug in x=1x = -1.

STEP 10

First, let's find the expression for (g+h)(x)(g + h)(x):
(g+h)(x)=g(x)+h(x)=4x2+x3(g + h)(x) = g(x) + h(x) = 4x^2 + x^3

STEP 11

Now, let's substitute x=1x = -1:
(g+h)(1)=4(1)2+(1)3(g + h)(-1) = 4(-1)^2 + (-1)^3

STEP 12

Remember, (1)2=1(-1)^2 = 1 and (1)3=1(-1)^3 = -1, so:
(g+h)(1)=4(1)+(1)=41=3(g + h)(-1) = 4(1) + (-1) = 4 - 1 = 3

SOLUTION

(gh)(x)=4x5(g \cdot h)(x) = 4x^5
(gh)(x)=4x2x3(g - h)(x) = 4x^2 - x^3
(g+h)(1)=3(g + h)(-1) = 3

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