If y varies directly as the square of x. When x = 2, y = 20, how do you find y when x = 4?
1 Answer
Apr 5, 2017
Explanation:
Note -
#color(blue)"the square of x is expressed as " x^2#
#rArrypropx^2# Make into an equation by introducing k, the constant of variation.
#rArry=kxxx^2=kx^2# To find k, use the condition given x = 2 when y = 20
#y=kx^2rArrk=y/x^2=20/4=5#
#"Thus " color(red)(bar(ul(|color(white)(2/2)color(black)(y=5x^2)color(white)(2/2)|)))#
#x=4toy=5xx4^2=80#