Tìm x,biết: a) (x+1)^2 =16 b)(3x – 2)^3 = 8 c) 5^x + 5^x-1 = 750

a) $(x+1)^2=16$

$↔ \left[ \begin{array}{l}x+1=4\\x+1=-4\end{array} \right.$

$↔ \left[ \begin{array}{l}x=3\\x=-5\end{array} \right.$

b) $(3x-2)^3=8$

$↔ (3x-2)^3=2^3$

$↔ 3x-2=2$

$↔ 3x=4$

$↔ x=\dfrac{4}{3}$

c) $5^x+5^{x-1}=750$

$↔ 5^x\Bigg(1+\dfrac{1}{5}\Bigg)=750$

$↔ 5^x.\dfrac{6}{5}=750$

$↔ 5^x=625$

$↔ 5^x=5^4$

$↔ x=4$