wtf? (1 Viewer)

[super.muppy]

a question from da one of the school certificates:
Micheal won $240. 'He donated Picture of his winnings to charity.' He divided the remainder between his savings and his investment account in the ratio 3:5

How much will he deposit in his savings account?
(A) $30
(b) $60
(C) $90
(D) $100

and da answer is 'B' but wat does the underlined part mean?

 

[rolror88]

Maybe its a "picture" of a fraction? Or some kind of symbol??

Cause if you work backwards, and you said the answer is B, then the remainder = $60 + $100 = $160. So is the picture 1/3 of his winnings to charity?

 

[Aznmichael92]

this question is not clear at all in my opinion

 

[TBK11]

hmm could be an error

 

[super.muppy]

help again

complete da perfect square
x^2-7x/3+__=(___)^2

fill in da blanks

 

[tommykins]

回复: help again

LHS blank is 49/36
RHS blank is (x-7/6)^2

 

[super.muppy]

Re: 回复: help again

LHS blank is 49/36
RHS blank is (x-7/6)^2

can u show working out plz

 

[tommykins]

回复: Re: 回复: help again

Well, say we have x^2 + ax + b where a and b is any number
Completing the square, you get

(x+a/2)^2 = x^2 + ax + b

Expanding the LHS side, we can see that a^2/4 = b in this case.

Now for your question
x^2-7x/3+__=(___)^2

here we have a = -7/3, half of this is -7/6
Completing the square, we have (x-7/6)^2

Squaring (-7/6) to obtain b (or you could use that b = a^2/4) we obtain (49/9)/4 = 49/36

 

[super.muppy]

help again last time 2day

5x^2 + 6x - 9 = 0

solve by completing the square

I did

x^2 + 6x/5 = 9/5
(x+3/5)^2=1/11/25
x= -3/5 plus or minus root 1/11/25

but dat doesn't seen to b the answer
where did i go wrong?

 

[cutemouse]

Re: help again last time 2day

To complete the square:

5x²+6x-9=0
Therefore x²+(6/5)x-(9/5)=0
(x+6/10)²-(36/100)-(9/5)=0
(x+6/10)²=216/100
(x+6/10)=+/-sqrt(216/100)

That should be correct, unless I've stuffed up somewhere.

 

[suzlee]

Re: help again last time 2day

hmmmm
I think you made a mistake in the line where you added the square of the halved number


edit: to jm01, I tried subbing your answers in but neither of them work...


edit: I did something and got:

[+_(sqrt54)-3]/5

But only the plus of the square root works;; No idea why


edit: Oooh I tried something else and I got this:

+_[sqrt(54/25)]-(3/5)

and both plus and minus work

 

[super.muppy]

Re: help again last time 2day

howd u get 6/10

 

[cutemouse]

Re: help again last time 2day

Hi,

I took away (6/5)² instead of (6/10)²

That *should* be correct now

 

[suzlee]

Re: help again last time 2day

howd u get 6/10

That's the same as 3/5 which is what you used, too.

 

[super.muppy]

Re: help again last time 2day

oh lol

 

[cutemouse]

Re: help again last time 2day

Or if you use the general quadratic formula you get:

x=[-6(+/-)sqrt205]/10

Hopefully I've done that one correctly haha.

 

[suzlee]

Re: help again last time 2day

I must be missing something; when I test my first solution, my calculator keeps giving me different things :S

 

[suzlee]

Re: help again last time 2day

Or if you use the general quadratic formula you get:

x=[-6(+/-)sqrt205]/10

Hopefully I've done that one correctly haha.

Subbing that doesn't give 0


edit: aha! It's 216 instead of 205

 

[super.muppy]

Re: help again last time 2day

hey do u ppl go to selective schools?

 

[suzlee]

no?

edit: oh this thread's been merged... I was wondering what just happened