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    Hello

    I'm stuck on this question, see attached. I have tried to do the working out and ended up with one correct answer (1) but there is another solution I missed (0). There must be an issue with my method - can anyone show me the correct way to approach this question and similar questions?

    It's question 7e on the second picture
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    Edit: didn't attach my working

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    (Original post by h8skoooooool)
    Hello

    I'm stuck on this question, see attached. I have tried to do the working out and ended up with one correct answer (1) but there is another solution I missed (0). There must be an issue with my method - can anyone show me the correct way to approach this question and similar questions?

    It's question 7e on the second picture
    It would help if you posted your method so we can see where you've gone wrong
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    (Original post by h8skoooooool)
    Hello

    I'm stuck on this question, see attached. I have tried to do the working out and ended up with one correct answer (1) but there is another solution I missed (0). There must be an issue with my method - can anyone show me the correct way to approach this question and similar questions?

    It's question 7e on the second picture
    easy you sub  5^x as y instead
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    (Original post by samb1234)
    It would help if you posted your method so we can see where you've gone wrong
    Sorry, it didn't attach - see above
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    You're meant to notice that 5^{2x} = (5^x)^2 so you have a quadratic in 5^x.

    Make the substitution u = 5^x to get u^2 - 6u - 5  = 0 then solve for u and back-substitute.
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    (Original post by h8skoooooool)
    Edit: didn't attach my working

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    Use a substitution and see if that could help us
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    (Original post by thefatone)
    easy you sub  5^x as y instead
    Oh so y^2 - 6y + 5 = 0 ?

    I feel like an idiot now haha, I was going to do that but it didn't seem right
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    (Original post by thefatone)
    easy you sub  5^x as y instead
    edit: \displaystyle 5^{2x} = 5^x \times 5^2
    That's incorrect. 5^x \times 5^2 = 5^{x+2} \neq 5^{2x}
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    (Original post by h8skoooooool)
    Oh so y^x - 6y + 5 = 0 ?

    I feel like an idiot now haha, I was going to do that but it didn't seem right
    Nah, y^2 not y^x. I assume it's just a typo though.
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    (Original post by Zacken)
    That's incorrect. 5^x \times 5^2 = 5^{x+2} \neq 5^{2x}
    yes i realised xD i deleted now xD
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    (Original post by Zacken)
    Nah, y^2 not y^x. I assume it's just a typo though.
    Yeah sorry it was, thanks a lot!
 
 
 
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