Tính: \(2\sqrt {{{( - 5)}^6}} + 3\sqrt {{{( - 2)}^8}} \).

* Hướng dẫn giải

\(\eqalign{
& 2\sqrt {{{( - 5)}^6}} + 3\sqrt {{{( - 2)}^8}} \cr 
& = 2.\sqrt {{{\left[ {{{\left( { - 5} \right)}^3}} \right]}^2}} + 3.\sqrt {{{\left[ {{{\left( { - 2} \right)}^4}} \right]}^2}} \cr} \)

\(\eqalign{
& = 2.\left| {{{( - 5)}^3}} \right| + 3.\left| {{{( - 2)}^4}} \right| \cr 
& = 2.\left| { - 125} \right| + 3.\left| {16} \right| \cr 
& = 2.125 + 3.16 = 298 \cr} \)