d are real numbers a1x+b1y+c1=0 a2x+b2y+c2=0 Where a1, b1, c1, a2, b2, c2 are all real numbers and a12+ b12 ≠ 0, a22+ b22 ≠ 0 The nth term of AP = nth term = a + (n-1) d Sum of n terms in AP ...