Question

Y is partly constantly and partly varies as x.when x=1,y=7 and when x=2,y=11.find the equation connecting x and y

Answer 1

y = m x + b
7 = m * 1 + b
11=m * 2 + b
----------------- subtract
-4 = -m
m = 4
7 = 4 + b
b = 3
so
y = 4 x + 3