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4(x+1)+4(1-x)=10 - Mathematics

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Question

`4^((x+1))+4^((1-x))=10`

Sum

Solution

`4^((x+1))+4^((1-x))=10` 

⇒ `4^(x + 1) + 4 · 4^x, 4^(1 - x) = 4/(4^x)`

⇒ `4 · 4^x + 4/(4^x) = 10`

Let `4x` be y. 

∴ `4y+4/y=10` 

⇒`4y^2-10y+4=0` 

⇒`4y^2-8y-2y+4=0` 

⇒`4y(y-2)-2(y-2)=0` 

⇒`y=2  or   y=2/4=1/2` 

⇒ `4^x=2  or  1/2` 

⇒`4^x=2^2x=2^1  or  2^(2x)=2^-1` 

⇒`x=1/2`   or `x= -(1)/2` 

Hence, `1/2`  and `-(1)/2`  are 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 72
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