Question

Tìm n thuộc R : (-8)^3.4^2n=(-2)^3n.164

Answer 1

ta có : \(\left(-8\right)^34^{2n}=\left(-2\right)^{3n}.164\Leftrightarrow\left(-2\right)^92^{4n}=\left(-2\right)^{3n}.164\)

\(\Leftrightarrow\dfrac{2^{4n}}{2^{3n}}=\dfrac{164}{2^9}\Leftrightarrow2^n=\dfrac{41}{128}\Leftrightarrow2^{n+7}=41\)

\(\Leftrightarrow n+7=log^{41}_2\Leftrightarrow n=log^{41}_2-7\)

vậy ...

Answer 2

\(\left(-8\right)^3.4^{2n}=\left(-2\right)^{3n}.164\)

đề vậy đúng ko