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.
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
REiny is right
To express R in terms of x and y, we need to analyze the relationship between R, x, and y.
Given that R varies partly as x and partly as the square of y, we can express this relationship as:
R = k * x * y^2
Where k is a constant of proportionality.
To find the value of k, let's use the given information:
When x = y = 1, R = 21:
21 = k * 1 * 1^2
21 = k
So, k = 21.
Now, we can express R in terms of x and y:
R = 21 * x * y^2
Therefore, the expression for R in terms of x and y is:
R = 21xy^2