How do you write an equation of a line given (-20,-10) and (5,15)?

2 Answers
Jun 20, 2018

#(y- -10)(5 - -20) = (x - -20)(15 - -10)#

#25(y+10)=25(x+20)#

#y=x+10#

Jun 20, 2018

Convert the equation into two-point slope form:
#y-y_1=(y_2-y_1)/(x_2-x_1) (x-x_2)# .

The resulting equation being:
#y+10=x-5#

Explanation:

Let #P_1# be #(-20,-10)#, with #x_1=-20# and #y_1=-10#,
#P_2# be #(5,15)#, with #x_2=5# and #y_2=15#,

By substitution,

#y-(-10)=(15-(-10))/(5-(-20)) (x-5)#

In evaluating,

#y+10=25/25(x-5)#

Further into:

#y+10=x-5# which serves as the final answer.

Source: http://mathworld.wolfram.com/Two-PointForm.html