Question

(a) A variable quantity y is equal to sum of two quantities, one of which varies directly
x and the other varies inversely as x. If y = 11 when x = 1 and y = 13 when x = 2, find
y when x = 3.​

Answer 1

Answer:

when x=3,

y= 17

Step-by-step explanation:

let y= a+b

a ∝ x and b ∝ 1/x

then a=mx and b=n/x

now y=mx + n/x

y=11 when x=1 gives , m + n = 11

y=13 when x=2 gives , 2m + n/2 = 13

solving this two equation we get

we get m=5 and n=6

now putting these values in y=mx + n/x

we get y=5x + 6/x

putting x=3 you will get y= 5x3 + 6/3 = 17.