Question

Function is a line points (3,2), (5,8), and (8,y) what is y

Answer 1

y = mx + b


`(3;\ 2)\to x_1=3;\ y_1=2\\\\(5;\ 8)\to x_2=5;\ y_2=8\\\\m=(y_2-y_1)/(x_2-x_1)\to m=(8-2)/(5-3)=(6)/(2)=3`

Therefore we have: y = 3x + b.

Put the coordinates of the point (3; 2) to the equation of the line:


`2 = 3\cdot3+b\\2=9+b\ \ \ |-9\\b=-7`

Therefore we have: y = 3x - 7

Substitute the coordinates of the point (8; y) to the equation of the line:


`y = 3\cdot8-7=24-7=17`

Answer: y = 17.