Binomial Theorem

If the magnitude of the coefficient of x⁷ in the expansion of \({\left( {a{x^2} + {1 \over {bx}}} \right)^8}\), where a, b are positive numbers, is equal to the magnitude of the coefficient of x⁷ in the expansion of \({\left( {ax + {1 \over {b{x^2}}}} \right)^8}\), then a and b are connected by the relation