Author Topic: Very basic question, but i can't answer it.. :( (Read 1441 times) Tweet Share

TheAspiringDoc · « **on:** November 03, 2014, 08:00:27 pm »

hi i've got some homework due in tomorrow and it has the question
solve for x and show workings.
2-(7x/2)=9
this question is really easy but I'm having a major mental blank.
Any help much appreciated
good luck in exams!

~V · « **Reply #1 on:** November 03, 2014, 08:04:52 pm »

Zealous · « **Reply #2 on:** November 03, 2014, 08:04:59 pm »

That's fine, everyone has a mental blank every now and then.

$\begin{eqnarray*}\\2-\frac{7x}{2} & = & 9\\2-\frac{7x}{2}+\frac{7x}{2} & = & 9+\frac{7x}{2}\\2 & = & 9+\frac{7x}{2}\\2-9 & = & 9+\frac{7x}{2}-9\\-7 & = & \frac{7x}{2}\\-7\times2 & = & \frac{7x}{2}\times2\\-14 & = & 7x\\\frac{-14}{7} & = & \frac{7x}{7}\\-2 & = & x\\x & = & -2\\\end{eqnarray*}$

Hope that helps!

Edit: oh ~V beat me by 7 seconds.

TheAspiringDoc · « **Reply #3 on:** November 03, 2014, 08:07:11 pm »

thank you both so much!

TheAspiringDoc · « **Reply #4 on:** November 04, 2014, 05:22:58 pm »

sorry for all the questions, but I seem to have come across another curveball.
$(x^2-9) = (x + 3)(x - 3)$
it seems like x can = 0,-3,3
how to prove this?
Thanks

TheAspiringDoc · « **Reply #5 on:** November 04, 2014, 06:42:05 pm »

OMG, i really can't math well at the moment. another question
mr fletcher is divorcing his wife. his lawyer is insisting he gets an annual allowance of $100,000 from his well-off wife so he can rear the children, pay fees etc for the next 15 years. assuming a hurdle rate of 4%, what lump sum today would provide that income flow?
i beleive it involves net present values and geometric progressions but am not sure.. thanks, TheAspiringDoc

Hannibal · « **Reply #6 on:** November 04, 2014, 07:24:06 pm »

Quote from: TheAspiringDoc on November 04, 2014, 05:22:58 pm

$(x^2-9) = (x + 3)(x - 3)$

$(x + 3)(x - 3)$ is the D.O.P.S format of $(x^2-9)$

This is because:
$(x+3)(x-3) = x^2 -3x +3x -9$
$(x+3)(x-3) = (x^2 -9)$

Because they are equal to each other x can be any value and the two sides of the equation will be the same. For example:

$x = 5$

$(x^2-9) = (x + 3)(x - 3)$
$(5^2-9) = (5 + 3)(5 - 3)$
$(25-9) = 8 * 2$
$16 = 16$

Not sure if that is what you were asking though.

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Author Topic: Very basic question, but i can't answer it.. :( (Read 1441 times) Tweet Share

TheAspiringDoc

Very basic question, but i can't answer it.. :(

~V

Re: Very basic question, but i can't answer it.. :(

Zealous

Re: Very basic question, but i can't answer it.. :(

TheAspiringDoc

Re: Very basic question, but i can't answer it.. :(

TheAspiringDoc

Re: Very basic question, but i can't answer it.. :(

TheAspiringDoc

Re: Very basic question, but i can't answer it.. :(

Hannibal

Re: Very basic question, but i can't answer it.. :(

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