Question
R varies partly as x and parly as the square of y. R=21 when x=y=1 and R=48 when x=y=2.Express R. in terms of x and y.
Answers
Reiny
R = a(x) + b(y^2)
case 1: R = 21, x = y = 1
21 = a + b
case 2: R = 48, x = y = 2
48 = 2a + 4b
or 24 = a + 2b
subtract them:
3 = b
then in a+b=21, a = 18
R = 18x + 3y^2
case 1: R = 21, x = y = 1
21 = a + b
case 2: R = 48, x = y = 2
48 = 2a + 4b
or 24 = a + 2b
subtract them:
3 = b
then in a+b=21, a = 18
R = 18x + 3y^2
carry on
REiny is right