## Functions Modeling Change: A Preparation for Calculus, 5th Edition

$r= \pm 5$
Square both sides of the equation to get $$|r^2+24|=7^2=49$$ Since $r^2+24$ is always greater than $0$, $|r^2+24|=r^2+24$. Thus, $$r^2+24=49$$ Subtract $24$ from both sides to get $$r^2=25$$ Finally, take the square root of both sides to get $$r=\pm 5$$