Question

Rút gọn rồi tính

a) 5√(-2)^4

b) -4√(-3)^6

c) √√(-5)^8 d) 2√(-5)^6+3√(-2)^8

Answer 1

Giải:

a) \(5\sqrt{\left(-2\right)^4}\)

\(=5\sqrt{2^4}\)

\(=5\sqrt{\left(2^2\right)^2}\)

\(=5.2^2\)

\(=20\)

b) \(-4\sqrt{\left(-3\right)^6}\)

\(=-4\sqrt{3^6}\)

\(=-4\sqrt{\left(3^3\right)^2}\)

\(=-4.3^3\)

\(=-108\)

c) \(\sqrt{\sqrt{\left(-5\right)^8}}\)

\(=\sqrt{\sqrt{5^8}}\)

\(=\sqrt{\sqrt{\left(5^4\right)^2}}\)

\(=\sqrt{5^4}\)

\(=5^2=25\)

d) \(2\sqrt{\left(-5\right)^6}+3\sqrt{\left(-2\right)^8}\)

\(=2\sqrt{5^6}+3\sqrt{2^8}\)

\(=2.5^3+3.2^4\)

\(=250+48\)

\(=298\)

Vậy ...