using indices only, and the substitution y=2^x , solve the equation: 2^2x - 6.2^x + 8 = 0
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Okay, could you perform the substitution?
Maybe it will help if you rewrite your equation as $\displaystyle \displaystyle \left(2^x\right)^2 - 6\cdot 2^x + 8 = 0$...
im lost as to where the substitution goes? and the question is written exactly as shown out of previous exam paper.
Look at Prove It's response. See those "$\displaystyle 2^x$"s? Replace those with y.
Originally Posted by HallsofIvy Look at Prove It's response. See those "$\displaystyle 2^x$"s? Replace those with y. And once you have done that, solve for $\displaystyle \displaystyle y$, the solution of which you can use to solve for $\displaystyle \displaystyle x$.
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