Question

let y varies directly us 2x+1 .if y=12 when x=3/2 then write a linear equation what is then value of y when x=7 ?​

Answer 1

answer : y = 45

explanation : y varies directly as (2x + 1)

or, y is directly proportional to (2x + 1)

or, y $\propto$ (2x + 1)

or, y = k(2x + 1), where k is proportionality constant.

given, x = 3/2 and y = 12

putting value of x and y in y = k(2x + 1)

or, 12 = k(2 × 3/2 + 1)

or, 12 = k(3 + 1)

or, 12 = 4k

or, k = 3

so, linear equation is, y = 3(2x + 1) = 6x + 3

now we have to find value of y if x = 7

so, putting x = 7 in equation, y = 6x + 3

i.e., y = 6 × 7 + 3 = 42 + 3 = 45

hence, value of y = 45