find equation in straight line

1.a)

(y-5)/(x-1) = (4-5)/(2-1) = -1/1 = -1

y-5 = (-1)(x-1)

y-5 = -x+1

x+y-6 = 0

b)

Put (7,-1) into the equation

value of 7+(-1)-6 = 0

(7,-1)satisfy the equation. therefore, L pass through (7,-1)

2014-01-23 20:49:10 補充：
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