What is the answer to 20a^{-2}+21a^{-1}-5=0 ?

The answer to 20a^{-2}+21a^{-1}-5=0 is a=-4/5 ,a=5

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20a^{-2}+21a^{-1}-5=0

20 a^{- 2} + 21 a^{- 1} - 5 = 0

a = - \frac{4}{5}, a = 5

Decimal Notation

a = - 0.8, a = 5

Solution steps

20 a^{- 2} + 21 a^{- 1} - 5 = 0

Refine

\frac{20}{a ^{2}} + \frac{21}{a} - 5 = 0

Multiply by LCM

20 + 21 a - 5 a^{2} = 0

Solve

20 + 21 a - 5 a^{2} = 0 : a = - \frac{4}{5}, a = 5

a = - \frac{4}{5}, a = 5

Verify Solutions

Find undefined (singularity) points:

a = 0

Combine undefined points with solutions:

a = - \frac{4}{5}, a = 5

\frac{1}{8} = \frac{1}{1 - 2 c}

\frac{8}{4 u - 8} - 1 = \frac{2}{u - 2}

\frac{7.5}{R} = 0.075

\frac{3}{k + 1} = \frac{12}{k - 12}

\frac{x ^{2} + 1}{x ^{2} - 1} = 0

What is the answer to 20a^{-2}+21a^{-1}-5=0 ?
The answer to 20a^{-2}+21a^{-1}-5=0 is a=-4/5 ,a=5
Solve for a: 20a^{-2}+21a^{-1}-5=0
The solution is a=-4/5 ,a=5