Answer
$12-7\sqrt{x}+x$
Work Step by Step
Use the FOIL method, along with
$\sqrt{a}\times\sqrt{b}=\sqrt{ab},\qquad$
$\sqrt{a^{2}}=(\sqrt{a})^{2}=a$ (for positive a).
$F:\quad 4\times 3=12$
$O:\quad 4\times(-\sqrt{x})=-4\sqrt{x}$
$I:\quad -\sqrt{x}\times 3=-3\sqrt{x}$
$L:\quad -\sqrt{x}\times(-\sqrt{x})=+(\sqrt{x})^{2}=x$
Add the terms (O and I are like terms...)
$...$= $12-7\sqrt{x}+x$
