## Thomas' Calculus 13th Edition

$x^2+y^2 \leq 9$ This is the region inside the circle $x^2+y^2=9$
We have $\iint_{R} (x^2+y^2-9) dA$ The integral must be minimum on the region when $x^2+y^2-9 \leq 0$ So, $x^2+y^2 \leq 9$ This is the region inside the circle $x^2+y^2=9$