Question

For all real values of c, the pair of equations: x-2y=8, 5x+10y=c have a unique solution. Justify whether it is true or false.

Answer 1

Answer:

a1× b2 - a2× b1 = 0 for parallel lines

1×10 - (5×-2) =20 so these lines are not parallel

slope 1 ×slope 2 = -1 for perpendicular lines

here these two lines are perpendicular lines

so it has unique solution