Question

Solve using Elimination method or cross multiplication method :
ax + by + a = 0, bx + ay + b = 0 .​

Answer 1

ax + by +a=0 -(1)

bx + ay + b = 0 -(2)

multiply eqn(1) with b and multiple eqn(2) with a

then abx+b^2+ab=0 -(3)

abx+a^2+ab=0 -(4)

subtract eqn(3) - eqn(4)

then (b^2-a^2)y=0

therefore y=0

substitute y=0 in eqn(1)

ax+b*0+a=0

ax=-a

therefore x=-1 y=0 is the solution