## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$4a^{2}+4a-3$
Substitute $2a$ for $x$ in the expression defining $f$: $f(2a)=(2a)^{2}+2(2a)-3$ $=2^{2}a^{2}+4a-3$ $=4a^{2}+4a-3$