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What is the input for the function f(x)=4x-9 if the output is 11

2 Answers

5 votes

Answer:

Input = 5

Explanation:

Output = Answer a.k.a. f(x)

Input = x

We start by replacing f(x) with the output, which is 11

11 = 4x-9. I like making it opposite. It's easier in my eyes.

Making it opposite it's 4x-9 = 11

Now we need to get x by itself. The opposite of -9 is +9. So if we add 9 to each side, it deletes the 9 from the left and puts it on the other side, making it;

4x = 11 + 9. 11 + 9 is 20, so....

4x = 20.

Now 4x is the same as 4 times x. The opposite of times is divide. So let's divide by 4 on both sides. That gets rid of the 4 on the left side and puts it on the other side, making it;

x = 20/4. 20/4 is 5, so...

x = 5

User Shay Erlichmen
by
8.1k points
5 votes

Explanation:

f(x) = 4x - 9

4x - 9 = 11

4x = 11 + 9

4x = 20

x = 20 ÷ 4

x = 5

User Arunkvelu
by
8.4k points

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