Question

If y is directly proportional to x^2, and y = 8 , when x = 4 , then find y when x =5

Answer 1

We know that if

           y ∝ x²

∴ y = k · x²

Now  

y = 8   , x = 4

From above y = k · x²

⇒ 8 = k · 4²

∴ k = 1/2

Again ....

x = 5  , y = ?

y = k·x²

y = 1/2 × 5²

  = 25/2 = 12.5

Thank u.

Answer 2

Answer:

5

Step-by-step explanation:

y = k × x²

8 = k × 2²

8 = k × 4

8 = 2 × 4

50 = 2 × x²

50 = 2 × 25²

50 = 2 × 5

x = 5