Y is directly proportional to x^2, if y=9 when x=3, find: a) the constant of proportionality.

k = 1

Step-by-step explanation:

=> y ∝ x²

So, y = kx²    (1)

Where k is the constant of proportionality

Now,

y = 9 when x = 3

Putting in (1)

=> 9 = k(3)²

=> 9 = k(9)

Dividing both sides by 9

=> k = 1

7.25

step-by-step explanation:

we know that 7 equals to 7.0. we also know that 1/4=0.25. so we can add the two together and we get 7.25

step-by-step explanation:

*calories burned = (weight)(calorie factor)*

calories burned = 180 (0.65)

calories burned = 117

the calories he used up is 117, which is 65% of his weight.