Giải bài 2.1 trang 99 - SBT Giải tích lớp 12

Tính

a) \(\dfrac{10^{2+\sqrt 7}}{2^{2+\sqrt 7}.5^{1+\sqrt 7}}\)

b) \((4^{2\sqrt 3}-4^{\sqrt 3-1}).2^{-2\sqrt 3}\)

Lời giải:

Hướng dẫn:

Áp dụng:

 \((a.b)^m=a^m.b^m\\ \dfrac{a^m}{a^n}=a^{m-n}\,\,\,\,(a\ne 0)\\ (a+b).c=ac+bc\)

a)

\(\dfrac{10^{2+\sqrt 7}}{2^{2+\sqrt 7}.5^{1+\sqrt 7}}=\dfrac{(2.5)^{2+\sqrt 7}}{2^{2+\sqrt 7}.5^{1+\sqrt 7}}\\ =\dfrac{2^{2+\sqrt 7}.5^{2+\sqrt 7}}{2^{2+\sqrt 7}.5^{1+\sqrt 7}}\\ =5\)

b)

\((4^{2\sqrt 3}-4^{\sqrt 3-1}).2^{-2\sqrt 3}=(2^{4\sqrt 3}-2^{2\sqrt 3-2}).2^{-2\sqrt 3}\\ =2^{4\sqrt 3-2\sqrt 3}-2^{2\sqrt 3-2-2\sqrt 3}\\ =2^{2\sqrt 3}-2^{-2}\\ =2^{2\sqrt 3}-\dfrac 1 4\)