## Precalculus (6th Edition) Blitzer

$2+5i$
RECALL: To divide the complex numbers $\dfrac{a+bi}{c-di}$, the conjugate of the denominator, which is $c+di$, must be multiplied to both the numerator and the denominator. Thus, the division $\dfrac{7+4i}{2-5i}$ requires multiplying $2+5i$ to both the numerator and the denominator.