Question

Rút gọn rồi tính :

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

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

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

Answer 1

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

b) \(-4\sqrt{\left(-3\right)^6}=-4\sqrt{\left(\left(-3\right)^3\right)^2}=-4\left|\left(-3\right)^3\right|\) = -4.27 = -108

\(c,2\sqrt{\left(-5\right)^6}+3\sqrt{\left(-2\right)^8}\) = \(2\sqrt{\left(\left(-5\right)^3\right)^2}+3\sqrt{\left(\left(-2\right)^4\right)^2}=2\left|\left(-5\right)^3\right|+3\left|\left(-2\right)^4\right|=2.125+3.16=298\)

Answer 2

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

b) \(-4\sqrt{\left(-3\right)^6}=-4\sqrt{\left(\left(-3\right)^3\right)^2}=-4\sqrt{\left(-27\right)^2}=-4\left|-27\right|=-4.27=-108\)

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

\(=2\sqrt{\left(-125\right)^2}+3\sqrt{16^2}=2\left|-125\right|+3\left|16\right|=2.125+3.16=250+48=298\)