Wednesday

April 1, 2015

April 1, 2015

Posted by **Mike** on Sunday, April 18, 2010 at 9:18am.

y varies directly as the square of R. If y = 128 when R = 8, find y when R = 5.

Another one I cannot figure out:

If x varies directly as y, and x = 32 when y = 8, find x when y = 10

Help!

- Math -
**Reiny**, Sunday, April 18, 2010 at 10:06amy varies directly as the square of R

becomes ...

y = k √R , where k is a constant

let's use the given information to find k

when y = 128, R = 8, then

128 = k√8

k = 128/√8 or 16√8 or 32√2

so y = 32√(2R)

when R = 5

y = 32√10 = appr. 101.19

- Math -
**Reiny**, Sunday, April 18, 2010 at 10:06amfor the second

x = ky, try doing it the same way as the first

**Answer this Question**

**Related Questions**

Variation - I have few questions that I need checked please and could you help ...

Math - DIRECT VARIATION 1. a is directly proportional to b.If a=15,then b=9 2. m...

math - This is about direct variation. The area a painter can paint varies ...

Algebra - This is about direct variation. The area a painter can paint varies ...

Math-Algebra - 1. The surface area of a cube varies directly as the square of ...

variation - Can you please check my answers? Thanxs! Write an equation that ...

variation - Can you please check my answers? Thanxs! Write an equation that ...

Variation-Check Problems - Can you please check my answers? Thanxs! Write an ...

Math help - 9). Hooke’s Law. The distance d when a spring is stretched by a ...

algebra - I have no clue what to do here can you tell me how to figure this? If ...