Question

Rút gọn rồi tính :

a) \(5\sqrt{\left(-2\right)^4}\)

b) \(-4\sqrt{\left(-3\right)^6}\)

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

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

Answer 1

a, \(5\sqrt{\left(-2\right)^4}=5\sqrt{2^4}=5.2^2=5.4=20\)

b, \(-4\sqrt{\left(-3\right)^6}=-4\sqrt{3^6}=-4.3^3=-4.27=-108\)

c,\(\sqrt{\sqrt{\left(-5\right)^8}}=\sqrt{\sqrt{5^8}}=\sqrt{5^4}=5^2=25\)

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

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

=\(2.5^3+3.2^4=2.125+3.16=298\)

Answer 2

a) \(5\sqrt{\left(-2\right)^4}\) \(=5\left|\left(-2\right)^2\right|=5.4=20\)

b) \(-4\sqrt{\left(-3\right)^6}=-4\left|\left(-3\right)^3\right|=-4.27=-108\)

c) \(\sqrt{\sqrt{\left(-5\right)^8}}=\left|\left(-5\right)^4\right|=5^4=625\)

d) \(2\sqrt{\left(-5\right)^6}+3\sqrt{\left(-2\right)^8}\) \(=2\left|\left(-5\right)^3\right|+3\left|\left(-2\right)^4\right|\)

\(=-2.\left(-125\right)+3.16\)

\(= 250 + 48 = 298\)