Question

Ok so I cant figure out why f(x) changes to 104 in this equation.
f(x)=√x+17-5. Why?

Answer 1

what do u mean f(x) changes to 104? is 104 the answer?

Answer 2

and it's Sqrt x+17 but the -5 isn't part of the square root right?

Answer 3

No ok so my math lab worked it out for me and this is how it did it.
f(x)=√x+17-5
f(104)=√104+17-5
=√121-5
=11-6
=5.

I wanna know why x changes to 104 I dont understand that.

Answer 4

It is.

Answer 5

ok, I get what u are saying, then the explanation is really simple.
We are replacing x with 104.

Answer 6

Yes but why? Lets say it where f(x)=√x+10-5 what wud x be now?

Answer 7

Lets use an example, say f(x) = x + 3 and I want to figure out f(3)
f(x) = x + 3
(3) = 3 + 3 = 6

Answer 8

We are simply substituting or replacing the value for x.

Answer 9

YOu can imagine f(x) is just y.

Answer 10

I forgot the f on the second line.
f(3) = 3 + 3 = 6***

Answer 11

f(x)=√x+10-5
putting it into words, we want to replace x with x, so the equation will be the same.
f(x)=√x+10-5
but if it is like this,
f(3)=√x+10-5
it will become this.
f(3)=√3+10-5
then solve.

Answer 12

x is the independent variable and f(x) (or y) is dependent on it, so as JayDs said sub 104 for x and you will get y

Answer 13

Man this isnt making sense.

Answer 14

sorry guys.

Answer 15

answer wold be 8

Answer 16

do you not understand my clear examples?

Answer 17

would I have to find the square root of 13?

Answer 18

and subtract that from 8

Answer 19

It is a simple substitution method. Maybe you should google it.
f(x) is the same thing as y
so saying f(x) = 3x + 5 is the same as y=3x + 5
f(x) = 3x + 5
f(3)- this means we want to replace x with 3.
f(x) = 3(3) + 5
= 9 + 5
=14

Answer 20

I would say unless specified saying "Round off to two decimal places or something else" leave it in exact form.

Answer 21

sorry its cause on my mathlab it teaches me to do it another way

Answer 22

is their more that 1 way to do it?

Answer 23

*Than

Answer 24

ok no problem but then their method must be really weird.

Answer 25

no there isn't, it is simply a "Substitution method"

Answer 26

f(x)=√x+17-5
f(104)=√104+17-5
=√121-5
=11-6
=5.

Answer 27

hence the word "Substitute" if you know what that means.

Answer 28

thats how they did it

Answer 29

are u familiar with that method

Answer 30

yes, it is the same thing as what I did.

Answer 31

but ur answer is wrong, it is not 5 by 6.

Answer 32

type it in a calculator and u will see that it is 6.

Answer 33

he/she/they (your maths lab) or whatever u call it has made a big mistake.

Answer 34

well for the last calculation part.

Answer 35

yeah it was 6 my mistake

Answer 36

I hope you understand the meaning and concept of "Substituting" it's basically saying I want whatever inside the bracket to be replaced with something else.
f(x) = 3x <<say this is given.
f(1) = ? we want to find this
putting it in words, I want to replace "x" with 1
f(1) = 3(1)
= 3

Answer 37

Ok understood

Answer 38

u know what happend i thought they werent giving me the value for x turns out they were lol. It was me that messed up.

Answer 39

lol, u shouldn't say that.

Answer 40

The most important thing is if you are stuck, ask ur math lab, teacher or whoever for classification.

Answer 41

Ok thank you. You were very helpful

Answer 42

no problem, as long as I could help u with ur problem.

Answer 43

excuse the repetition of the word problem lol.