garis y= 2x+a dan y= bx-1 berpotongan di titik (1,5). nilai a-b=

Titik potong = (1, 5)
1) y = 2x + a
=> 5 = 2(1) + a
=> 5 = 2 + a
=> a = 3
2) y = bx - 1
=> 5 = b(1) - 1
=> 6 = b

a - b = 3 - 6 = -3