Math  /  Algebra

QuestionFind the value of (fg)(2)(f \circ g)(2) f(x)=5x+2f(x) = 5x + 2 and g(x)=3x4g(x) = 3x - 4

Studdy Solution

STEP 1

What is this asking? We need to find the value of a composite function at a specific point, meaning we'll plug a number into one function, then plug *that* result into another function! Watch out! Remember the order matters with composite functions! (fg)(x)(f \circ g)(x) means we apply gg *first*, then ff.
It's like a tiny assembly line for numbers!

STEP 2

1. Evaluate g(2)g(2)
2. Evaluate f(g(2))f(g(2))

STEP 3

Let's **kick things off** by evaluating g(2)g(2).
We're doing this because gg is the *inner* function in our composite function.
Remember, we work from the inside out!

STEP 4

We know that g(x)=3x4g(x) = 3x - 4, so we **substitute** xx with our **input value**, which is 22: g(2)=324g(2) = 3 \cdot 2 - 4

STEP 5

Now, we **simplify**: g(2)=64g(2) = 6 - 4 g(2)=2g(2) = 2So, g(2)g(2) equals **2**!
This **intermediate result** is what we'll plug into ff next.

STEP 6

We just found that g(2)=2g(2) = 2, so (fg)(2)(f \circ g)(2) is the same as f(g(2))f(g(2)), which is the same as f(2)f(2).
We're doing this because we've simplified the inside of the composite function, and now we're ready to tackle the outside function, ff.

STEP 7

We know that f(x)=5x+2f(x) = 5x + 2, so let's **substitute** xx with our **new input**, which is 22: f(2)=52+2f(2) = 5 \cdot 2 + 2

STEP 8

Time to **simplify**: f(2)=10+2f(2) = 10 + 2 f(2)=12f(2) = 12So, f(2)f(2), which is the same as f(g(2))f(g(2)), equals **12**!

STEP 9

(fg)(2)=12(f \circ g)(2) = 12

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