Question

Pre-calculus question

Answer 1

what's the equation for inverse variation ?

Answer 2

for direct variation y = kx
and for inverse variation ? do you know ?

Answer 3

c

Answer 4

equation for inverse variation \[\huge\rm y = \frac{k}{x}\]
where k is constant of variation
in this case y inversely as the `square ` of x
so it would be \[\huge\rm y = \frac{k}{x^2}\]

Answer 5

now substitute x and y for their values to find value of k

Answer 6

1/8=k/5

1/8=k/5^2 right?

Answer 7

to find k we should know both x and y value
when y =1/8 x =1 not 5

Answer 8

so substitute x for 1

Answer 9

1/8=k/1

1/8=k/1^2 ?

Answer 10

looks good

Answer 11

Ok so how do I simplify?

Answer 12

well 1^2 is same as 1
\[\frac{1}{8}=\frac{k}{1}\]
and k /1 = k
plugin k value into the original equation

Answer 13

Wait but what is the value of k??

Answer 14

\[\rm \frac{k}{1} =\frac{1}{8}\]
k= ???

Answer 15

you don't need solve that
k/1 is just k
k=?

Answer 16

k=1?

Answer 17

hmm here is an example \[\frac{x}{1}= 2 ~~~~~~~x=2\]

Answer 18

So k=2?

Answer 19

hmm that's an example

Answer 20

\(\color{blue}{\text{Originally Posted by}}\) @Nnesha
\[\rm \frac{k}{1} =\frac{1}{8}\]
k= ???
\(\color{blue}{\text{End of Quote}}\)
k = ?

Answer 21

\[\huge\rm \color{Red}{\frac{ k }{ 1 }}=\frac{1}{8} \]\[\large\rm \color{Red}{k}=??\]
we didn't add subtract anything
just change k/1 to k right side would stay the same

Answer 22

k = 1/8(1) ?

Answer 23

yeah which is same as 1/8 now substitute k for 1/8 into the original equation

Answer 24

1/8=(1/8)/(1)

1/8=(1/8)/1^2

Answer 25

\[\huge\rm y= \frac{k}{x^2}\]
substitute just `k` for 1/8

Answer 26

gone?

Answer 27

Ok I'm back! So I got C as the answer! Thanks @Nnesha :D

Answer 28

that's not correct.

Answer 29

k = 1/8
replace k with 1/8 into the original equation \[\huge\rm y=\frac{ \color{reD}{k} }{ x^2 }\]

Answer 30

I got it right, though...

Answer 31

are you sure ??

Answer 32

Yeah that's so weird...I got it right. What did you think it was? I'm going to email my teacher.

Answer 33

tell ur teacher that's not correct. \[\frac{ k }{ x^2 } =\frac{ \frac{1}{8} }{ \frac{x^2}{1} }\]
x^2 is saem as x^2/1
we should multiply the top fraction with the `reciprocal` of the bottom fraction

Answer 34

So I tell him that B is the correct answer?

Answer 35

ye

Answer 36

Ok thanks nnesha

Answer 37

yw