Question

Observe the following graph and write the equation of line AB and line CD with justification​

Answer 1

The equation of line AB is y = x + 1 and line CD is 9y + 8x = 36

The general equation of line passing through 2 known points ( xo,yo) and (x1,y1)  is :

• (y - yo)/(x - xo) = (y1 - yo )/ (x1 - xo)

Given

• AB passes through ( 0,1 ) and ( -1 , 0)

Therefore equation of AB =

• y - 1 / x = 0 - 1 / -1 - 0 = 1

Therefore equation of AB

• = y - 1 = x

• Equation of AB ==> y = x + 1

Similarly equation of CD:

• CD passes through ( 4.5,0) and ( 0 , 4 )

Therefore equation of CD =

• y - 0 / x - 4.5 = 4 - 0 /  0 - 4.5 = -4/4.5 = -8/9

Therefore equation of CD =

• 9y = -8( x - 4.5) = -8x + 36

• Equation of CD ==> 9y + 8x = 36