PROBLEM
Suppose that the functions g and h are defined for all real numbers x as follows.
g(x)=4x2h(x)=x3 Write the expressions for (g⋅h)(x) and (g−h)(x) and evaluate (g+h)(−1).
(g⋅h)(x)=□(g−h)(x)=□(g+h)(−1)=□
STEP 1
What is this asking?
We're given two functions, g(x) and 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=−1.
Watch out!
Don't mix up multiplying functions with multiplying regular numbers!
Also, remember that (−1)2 is positive, but (−1)3 is negative.
STEP 2
1. Find (g⋅h)(x)
2. Find (g−h)(x)
3. Evaluate (g+h)(−1)
STEP 3
Alright, let's multiply those functions!
We're given g(x)=4x2 and h(x)=x3.
So, (g⋅h)(x) just means g(x)⋅h(x).
STEP 4
Let's substitute the expressions for g(x) and h(x):
(g⋅h)(x)=(4x2)⋅(x3)
STEP 5
Now, we multiply the coefficients and add the exponents of x:
(g⋅h)(x)=4x2+3=4x5 So, (g⋅h)(x)=4x5!
STEP 6
Time to subtract! (g−h)(x) means g(x)−h(x).
STEP 7
Let's substitute again:
(g−h)(x)=(4x2)−(x3)
STEP 8
We can rewrite this as:
(g−h)(x)=4x2−x3 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=−1.
STEP 10
First, let's find the expression for (g+h)(x):
(g+h)(x)=g(x)+h(x)=4x2+x3
STEP 11
Now, let's substitute x=−1:
(g+h)(−1)=4(−1)2+(−1)3
STEP 12
Remember, (−1)2=1 and (−1)3=−1, so:
(g+h)(−1)=4(1)+(−1)=4−1=3
SOLUTION
(g⋅h)(x)=4x5
(g−h)(x)=4x2−x3
(g+h)(−1)=3
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