Question

for what value of a, the pair if linear equation. ax+3y=a-3,12x+ay=a has no solutions?

Answer 1

no solution means the lines are parallel
i.e, condition for parallel lines is
$a1 \div a2 = b1 \div b2isnotequal \: to \: c1 \div c2$
now
$a \div 12 = 3 \div a \\ a ^{2} = 36 \\ a = + - 6$