Question

Help!! I'm doing homework right now and I'm really struggling with it. could anyone walk me though f(x)=3|2x-1|+x find f(-4)

Answer 1

Try simplifying this.
\[3(2x + 1)\]
Can be simplified to
\[5x + 5\]
by multiplying the inside of the brackets by 3.

Answer 2

okay that makes since can you keep explaining? I'm kinda getting it

Answer 3

This makes the sum
\[f(x) = (5x + 5) + x\]

You can simplify it further by removing the '+x' by putting it inside the brackets. That gives you

\[F(x) = 6x + 5\]

Now try removing x from the first side. That'll give you f.
Remember, what ever you do to one side you must do to the other.

Answer 4

so to get f by itself would I multiply x or 5?

Answer 5

I mean subtract

Answer 6

F(x) is F times X, so you remove the x by dividing both sides by x.

Answer 7

okay so if I do that I get f=6x+4 ? I'm sorry this is so confusing.

Answer 8

Huh?
Ok.
6x divided by x is 6. does that help?

Answer 9

OH so f=6+5?

Answer 10

Yeah.

Answer 11

NO WAIT GOD IT'S A FUNCTION

Answer 12

ERASE EVERYTHING I JUST SAID

Answer 13

GOD I'm SO SORRY

Answer 14

it's okay haha

Answer 15

Right. This is much easier, actually.
Don't actually erase everything, because the simplification still stands
You just need to work out
\[6x + 5\]
if X is -4.

Answer 16

that was my bad I should of told you😂

Answer 17

so would I do 6•-4+5?

Answer 18

No, I was a muppet and completely forgot F(x) means x is input thus function.

Answer 19

Yeah, exactly. For real and proper this time :)

Answer 20

okay so is that all since I found -4's function or is there more?(:

Answer 21

Yup, that's all. For functions, if you need to find f and you have the input, you just substitute the input for x.

Answer 22

thank you so much this makes total since now! you are a life saver

Answer 23

On the plus side, you now know how to solve both\[fx = 3(2x+1) + x\] and \[f(x) 3(2x + 1) +x\] which are for some reason completely different.

Answer 24

No problem! Thank you for forgiving my muppetosity :)

Answer 25

so my answer to this problem is just 6•-4+5

Answer 26

Yeah.

Answer 27

okay thank you again

Answer 28

NO

Answer 29

GOD NOT AGAIN I'M SO STUPID

It doesn't simplify to 5x + 5. It's 6x + 3.

So
\[F(-4) = (6x + 3) + x\]
equals
\[F(-4) = (7 \times -4) +3\]

So F(-4) = -25.


This time I'm pretty sure I'm right, but give me a minute and I'm sure I'll find out I'm counting in the wrong language or something.