Giải thích các bước giải:
$a,M=4\sqrt[]{25u} -\frac{15}{2}.\sqrt[]{\frac{16u}{9} }-\frac{2}{u}\sqrt[]{\frac{169u^2}{4}}$
Đk: $u>0$
$⇔M=20\sqrt[]{u} -10\sqrt[]{u }-13$
$⇔M=10\sqrt[]{u}-13$
$b,N=\frac{t}{2}+\frac{3}{2}\sqrt[]{4-4t+t^2}-2$
Đk: $t≤2$
$N=\frac{t}{2}+\frac{3}{2}\sqrt[]{(2-t)^2}-2$
$⇔N=\frac{t}{2}+\frac{3}{2}.(2-t)-2$
$⇔N=\frac{t+3(2-t)-4}{2}$
$⇔N=\frac{t+6-3t-4}{2}=1-t$
