## Calculus (3rd Edition)

$x+y=10$ $\implies y=10-x$ Substituting the value of y in $xy=24$, we have $x(10-x)=24$ or $10x-x^{2}=24$ or $x^{2}-10x+24=0$ x=$\frac{-b±\sqrt {b^{2}-4ac}}{2a}=\frac{10±\sqrt {100-4\times1\times24}}{2}$ $x=6$ or $x=4$ If x is 6 y is (10-6)=4. If x is 4, y is 6.