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Let ​f(x)=3x-5 and ​g(x)=4-x^2. Evaluate each expression symbolically. ​(a) ​(f+​g)(3​) ​(b) ​(f-​g)(- 2​) ​(c) ​(fg)(1​) ​(d) (StartFraction f Over g EndFraction )​(5​)

User SalkinD
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Answer:

a) -1

b) -11

c) -6

d) -10/21

Explanation:

We have that


f(x) = 3x - 5


g(x) = 4 - x^(2)

So


(f + g)(x) = 3x - 5 + 4 - x^(2) = -x^(2) + 3x - 1


(f-g)(x) = 3x - 5 - 4 + x^(2) = x^(2) + 3x - 9


(fg)(x) = (3x - 5)(4 - x^(2))


(f)/(g)(x) = \frac{3x - 5}{4 - x^(2))

(a) ​(f+​g)(3​)


(f + g)(x) = 3x - 5 + 4 - x^(2) = -x^(2) + 3x - 1

We replace x by 3. So


(f+g)(3) = -3^(2) + 3*3 - 1 = -1

(b) ​(f-​g)(- 2​)


(f-g)(x) = 3x - 5 - 4 + x^(2) = x^(2) + 3x - 9

We replace x by -2. So


(f-g)(-2) = (-2)^(2) + 3(-2) - 9 = -11

​(c) ​(fg)(1​)


(fg)(x) = (3x - 5)(4 - x^(2))

We replace x by 1. So


(fg)(1) = (3*1 - 5)(4 - (1)^(2)) = -6

(d) (f/g)​(5​)


(f)/(g)(x) = \frac{3x - 5}{4 - x^(2))

We replace x by 5. So


(f)/(g)(x) = \frac{3*5 - 5}{4 - (5)^(2)) = -(10)/(21)

User Hjblok
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