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`3^((X+2))+3^(-x)=10` - Mathematics

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Question

`3^((x+2))+3^(-x)=10`

Solution

`3^((x+2))+3^(-x)=10` 

`3^(x)9+1/3^(x)=10` 

Let `3^x` be equal to y. 

∴` 9y+1/y=10` 

⇒`9y^2+10y+1=0` 

⇒`9y^2-10y+1=0` 

⇒`(y-1) (9y-1)=0` 

⇒`y=1  or   y=1/9` 

⇒`3x^x=1  or  3^x=1/9` 

⇒`3^x=3^0  or  3^x=3^-2` 

⇒`x=0  or  x=-2` 

Hence, 0 and -2 are the roots of the given equation.

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Chapter 10: Quadratic Equations - Exercises 1

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RS Aggarwal Mathematics [English] Class 10
Chapter 10 Quadratic Equations
Exercises 1 | Q 71
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