Question

Y is directly proportional to x² and y = 50 when x =5, Find

i) Equation connecting x and y
ii) The value of y when x= 4
iii) The value of x when y= 200 ​

Answer 1

Equation: y = 2(x^2)

Y-value = 32

X-value = 10

Explanation:

y = k(x^2)

k symbolises proportionality.

solve for k:

50 = k(5^2)

50 = 25k

k =2

So...

equation is y = 2(x^2)

Value of y when x = 4,

y = 2 x 4^2

y = 2 x16

y = 32

Value of x when y = 200,

200 = 2(x^2)

100 = x^2

x = 10