Question

if y is directly proportional to x and y= 20 when x=4 find an equation connecting x and y

Answer 1

Explanation:

the initial statement is

y

∝

x

to convert to an equation multiply by k the constant

of variation

⇒

y

=

k

x

to find k use the given condition

y

=

5

when

x

=

2

y

=

k

x

⇒

k

=

y

x

=

5

2

equation is

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

∣

∣

∣

2

2

y

=

5

2

x

=

5

x

2

2

2

∣

∣

∣

−−−−−−−−−−−−−−−−−−

when

x

=

16

then

y

=

5

2

1

×

16

8

=

5

×

8

=

40

Answer link