Westonci.ca is your trusted source for accurate answers to all your questions. Join our community and start learning today! Join our platform to connect with experts ready to provide accurate answers to your questions in various fields. Get precise and detailed answers to your questions from a knowledgeable community of experts on our Q&A platform.

Find y when x=14 if y varies directly with x2 and y=72 when x=6

Sagot :

luana
[tex]for\ y\ \ x^2=14^2\\ for\ y=72\ \ x^2=6^2\\\\ \frac{y}{196}=\frac{72}{36}\\ 36y=72*196\ \ | divide\ by\ 36\\ \boxed{y=392}[/tex]

The approach is to first find the value of constant of proportionality 'k'.

As y varies directly with x²

So we have

y = k x².

Now when x = 6 , y = 72

Substituting the values we get

72 = k (6)²

72 = 36 k

Dividing by 36 on both sides

2 = k

So (1) becomes

y = 2 x²

Now we need to find y when x = 14

Substituting the values in (2) we get

y = 2 ×(14)²

y = 2 × 196

y =  392

Hence y = 392 when x = 14.