How do we find the equation of line joining #A(0,0)# and #B(3,-3)#?

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Answer 1 · 2016-11-26T07:45:41

#x+y=0#

Method 1 - Equation of a line joining points #(x_1,y_1)# and #(x_2,y_2)# is given by

#(y-y_1)/(y_2-y_1)=(x-x_1)/(x_2-x_1)#

Hence equation of line joining #A(0,0)# and #B(3,-3)# is

#(y-0)/(-3-0)=(x-0)/(3-0)#

or #y/-3=x/3#

or #-y=x# i.e. #x+y=0#

Method 2 - As one point is #(0,0)#, #y#-intercept is #0# and hence equation is of type #y=mx#.

As it passes through#B(3,-3)#, we have

#-3=mxx3# or #m=-3/3=-1#

Hence equation is #y=-1xx x# or #y=-x# or #x+y=0#