Author Topic: Methods 1/2 Question. (Read 3958 times) Tweet Share

IndefatigableLover · « **Reply #15 on:** August 17, 2014, 08:21:04 pm »

Quote from: M-D on August 17, 2014, 07:46:46 pm

I've got another question now on exponentials. It's: solve for x: $2^x+2^{-x+1}=3$ . Please show working out. Thanks

$2^x+2^{-x+1}-3=0$ (Multiply both sides by $2^x$ )

$\therefore 2^{2x}-3\times 2^x+2=0$ (Let $2^x=y$ )

$\therefore y^2-3y+2=0$

$\therefore y=1,2$

Sub back what 'y' equals and you'll find that your 'x' values equal 0 and 1

M-D · « **Reply #16 on:** August 17, 2014, 08:37:10 pm »

Thanks IndefatigableLover.

Damo23 · « **Reply #17 on:** September 09, 2014, 04:57:46 pm »

Anyone here know how to do this
Find a and k such that the graph of y = a10^kx passes through the points (2, 6) and
(5, 20).

And is this like group like where all the unit 1/2 questions methods r asked or is there a bigger group?
I just was wondering

dankfrank420 · « **Reply #18 on:** September 09, 2014, 05:20:49 pm »

Set up simultaneous equations (sub your x and y values in).

Solve from there.

Damo23 · « **Reply #19 on:** September 09, 2014, 05:28:44 pm »

Quote from: dankfrank420 on September 09, 2014, 05:20:49 pm

Set up simultaneous equations (sub your x and y values in).

Solve from there.

Yeh I've tried that already but I can't get past it

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Author Topic: Methods 1/2 Question. (Read 3958 times) Tweet Share

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