A = ( 4 , 3 ) ..**&**.. B = ( - 1 , 1 )
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Slope = [ y(B) - y(A) ] ÷ [ x(B) - x(A) ]
Slope = [ 1 - 3 ] ÷ [ - 1 - 4 ]
Slope = [ - 2 ] ÷ [ - 5 ]
Slope = 2/5
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y - y(0) = Slope × ( x - x(0) )
y - y(A) = Slope × ( x - x(A) )
y - 3 = 2/5 × ( x - 4 )
y - 3 = 2/5 x - 8/5
y = 2/5 x - 8/5 + 3
y = 2/5 x - 8/5 + 15/5
y = 2/5 x + 7/5