Question

For each function find f(-2), f(-0.5), and f(3)

Are these correct

8. F(x)= 3/8x -3

1. F= -8
2. F= 4.6
3. F=2.3

Answer 1

f(x) = (3/8) * x - 3

or is that x supposed to be part of that denominator

Answer 2

group the thing with bra-kets for fractions , not sure how you got -8 for the first

f(-2), replace x with -2, evaluate for what f(x)=

Answer 3

I'm sorry I don't understand ): can you show me how to do the first one and I'll do the other two

Answer 4

yes, did i type it in right, the x is multiplied by 3/8 right, it is not 3/(8x) is it

Answer 5

Correct (: it is multiplied by 3/8

Answer 6

f(-2) is the value of f(x) when x=-2, let x=-2, substitute -2 in for all x's


f(-2) = (3/8) *(-2) - 3

= -6/8 - 3

Answer 7

negative six eights minus 3, then simplify more, let 3 become 24/8, to have same denominator , so we can combine fractions

Answer 8

-(6/8) - (24/8) = -30/8

Answer 9

you can reduce that to -15/4

f(-2) = -15/4

Answer 10

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if x=3 like the last one to figure f(3) you get (9/8) - 3 simplify

Answer 11

Do I do anything with the -2?

Answer 12

no, -2 is just the x value, f(-2) is the y value for a point on the graph of the function

Answer 13

My problem is multiplying with fractions

Answer 14

the function f(x) takes any x value you pick along the horizontal x axis, and gives it a y value, it is a rule machine to go from a chosen x value to a corresponding y value

Answer 15

\[\frac{ a }{ b } * \frac{ c }{ d }=\frac{ a*c }{ b*d }\]

you just multiply top and bottom seperate like that

Answer 16

so for 9/8 times -2, you can think of -2 as -2/1

Answer 17

the negative 2 multiplies into the numerator

Answer 18

Oh okay that makes sense (: okay one sec I'm gonna do the problems let me know if they are right (:

Answer 19

to be able to add the fractions, i had to make them both over the same denominator. i multiplied -3 by 8/8 ,

Answer 20

So I got f(-0.5)= 2.6

Answer 21

let's see what you did .

they are mixing decimals and fractions, it is messy you can keep x as -0.5 or make it -1/2

Answer 22

f(-0.5) = (-1.5)/8 - 3

Answer 23

can you do the arithmetic with a calculator? for class

Answer 24

I did 3/8 multiplied by -1/2 instead of -0.5 then I got -3/16 -3 then I put a 1 under the 3 to make it -3/16 - 3/1 and I got -6/16

Answer 25

Is it -3/8

Answer 26

you were on the right traack, remember to add or subtract fractions, they have to be both over the same denominator

-3/16 - 3*(16/16)

Answer 27

I don't understand that part ☹

Answer 28

you got the multiplying fractions down, multiply top and bottom together individually

addition and subtraction requires the same denominator first

Answer 29

you can add 16ths to 16ths, but you cant add 16ths to 87ths without changing things, the bottom has to be the same

Answer 30

\[\frac{ a }{ c } + \frac{ b }{ c } = \frac{ (a+b) }{ c }\]

Answer 31

Can we start over

Okay so the problem is f(x) = 3/8 (-0.5)-3

F(-0.5) = 3/8 times -0.5

Then what?

Answer 32

we can keep the -1/2 you used, you did that part right

(-3/16) - 3

from here you have to put the whole number 3 into 16ths, need same denominator to combine fractions

Answer 33

Would you be fine doing this with me through snapchat so I can show you what I did

Answer 34

i dont have that

Answer 35

multiply the 3 by (16/16)


16/16 is just 1, you are only multiplying by 1, it doesnt change anything

Answer 36

it becomes 48/16 which is the same as 3

Answer 37

So -3/16 -3 times 16/16?

Answer 38

yep.. review "common denominators" if you forgot about that
...
then you can combine fractions, -3/16 - 48/16

Answer 39

-51/16 or you can approximate with decimals since x is a decimal

Answer 40

Answer : f(-0.5)= -9

Answer 41

Oh nevermind you add not multiply woods

Answer 42

-3.18 is the answer??

Answer 43

-51/16, is that what the calculator says.. looks right

Answer 44

-3.1875

Answer 45

Go for the last one, ill check it at the end, nothing new just a different x value

Answer 46

Thank you!!!!Can you help me with the last one?

Answer 47

Ok so f(3) = 3/8 (3)-3 correct?

Answer 48

6/8 -3?

Answer 49

Is this the answer??

F(3) = 3.75

Answer 50

@DanJS

Answer 51

sorry missed this notification,

if x is 3

\[f(3) = \frac{ 3 }{ 8 }*3 - 3 ~~~~ =~~~~\frac{ 9 }{ 8 } - \frac{ 24 }{ 8 } \]

Answer 52

= (9-24) /8 = -15/8

Answer 53

you just need to practice adding vs multiplying fractions, this time you added the numerators in the (3/8)*3

Answer 54

Oh okay thank you so so much!!! Your awesome (:

Answer 55

remember the rules, i think i typed them with the a,b,c,d, general fractions somewhere here

Answer 56

Would you mind helping me with a new problem?

Answer 57

And I will thank you(:

Answer 58

ok

Answer 59

It's fine I'm going to bed thank you for your help! (:

Answer 60

ok, welcome, i may be on tomorrow also if you are working