Solving algebraically

How to solve these algebraically? 

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a)

$\color{BrickRed}-2+5z^{-\frac{3}{2}}=133\\ 5z^{-\frac{3}{2}}=135\\ z^{-\frac{3}{2}}=27\\ z^{-3}=27^2\\ z^3=\frac{1}{27^2}\\ z=\frac{1}{\sqrt[3]{(3^3)^2}}$

$z=\frac{1}{9}$

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How to solve these algebraically? 

Hello Guest!

b)

$\color{BrickRed}2,1x^{0,25}+5=7\\ x^{\frac{1}{4}}=\frac{2}{2,1}\\ x=(\frac{2}{2,1})^4$

$x=(\frac{20}{21})^4=(\frac{2^2\cdot 5}{3\cdot 7})^4$

$x=\frac{2^8\cdot 5^4}{3^4\cdot7^4}=0,8227...$

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How to solve these algebraically? 

a)

b)