O-Level Additional Math

[mum_sugoku]

rubydoll:

Dear sir


Very sorry the attachment did not come in.

The sum is (1/2) x = (8) x-2

It is Half to the power of x = 8 to the power of x minus 2.

Thanks
Regards
Rubydoll

(1/2)^x ==> (2^-1)^x, or 2^(-x)
8^(x-2) ==> (2^3)^(x-2), or 2^[3(x-2)]

therefore 2^(-x) = 2^[3(x-2)]
==> -x=3(x-2)
solving for x, you'll get x=3/2

[Eddow]

mum_sugoku:

JadeDry:

@ Eddow & Pinkapple


I checked the question, it still is: 9(x to the power of ab) - ((xy) to the power of ab) - 9(y to the power of ab) - 81

I would appreciate more help if you do not mind.

Which is the simplest form?:

(4X- 8Y) or 4(X-2Y)

And why?

Thanks in advance.

If question is .... \"+\" ((xy) to the power of ab).... instead of \"-\", then solution is (x^ab -9) (y^ab +9)..

I suspect printing error in the question. If it's ....+81, then answer should be (x^ab +9) (9 - y^ab)

For question like this...Which is the simplest form?:
(4X- 8Y) or 4(X-2Y) .
If the question is asking you to FACTORISE, then correct ans is 4(x-2y).

[Eddow]

[quote]

If question is .... \"+\" ((xy) to the power of ab).... instead of \"-\", then solution is (x^ab -9) (y^ab +9)..[/quote](x^ab -9) (y^ab +9) is not the ans as this is a diff of 2 sq, which will results in x^(2ab) -81, which is not the question.

[mum_sugoku]

Eddow:

[quote]

If question is .... \"+\" ((xy) to the power of ab).... instead of \"-\", then solution is (x^ab -9) (y^ab +9)..

(x^ab -9) (y^ab +9) is not the ans as this is a diff of 2 sq, which will results in x^(2ab) -81, which is not the question.[/quote]Haha x^ab times y^ab will not give you x^2ab mah..

(x^ab-9)(y^ab+9)= (x^ab)(y^ab) - (9)(y^ab) + (9)(x^ab) -(9)(9)

=(xy)^ab -9(y^ab) +9(x^ab) - 81

[mum_sugoku]

Eddow:

[quote]

If question is .... \"+\" ((xy) to the power of ab).... instead of \"-\", then solution is (x^ab -9) (y^ab +9)..

(x^ab -9) (y^ab +9) is not the ans as this is a diff of 2 sq, which will results in x^(2ab) -81, which is not the question.[/quote]Haha x^ab times y^ab will not give you x^2ab mah..

(x^ab-9)(y^ab+9)= (x^ab)(y^ab) - (9)(y^ab) + (9)(x^ab) -(9)(9)

=(xy)^ab -9(y^ab) +9(x^ab) - 81 !!!

[Eddow]

Eddow:

[quote]

(x^ab -9) (y^ab +9) is not the ans as this is a diff of 2 sq, which will results in x^(2ab) -81, which is not the question.

[/quote]Oops... see wrongly , there's a y^ab.. so it's not diff of 2 sq.

[Eddow]

Haha x^ab times y^ab will not give you x^2ab mah..


(x^ab-9)(y^ab+9)= (x^ab)(y^ab) - (9)(y^ab) + (9)(x^ab) -(9)(9)

=(xy)^ab -9(y^ab) +9(x^ab) - 81[/quote]

oh.. you're assuming +9(x^ab) - 81. And I'm assuming -9(x^ab) +81, that's why ans diff.

It's just printing error in the original question.

[Eddow]

bigmac:

Here is the question:


Find the smallest number which when divided by 24 and 36 leaves a remainder of 11.

Solution given by the book:
LCM: 2X2X2X3X3
=8X9=72

Thus, require number = 72 + 11 = 83

Can explain to me why need to add the 11.

Thanks alot.

.

Because there is a remainder of 11.
If you only find the LCM of 24 and 36, you will get the 72.

[Eddow]

carebear:

How to do 3+4+5+6.....+200


and 10+12+14+16+.....+400?

TIA.
:oops:

First, find how many number are there from 3 to 200 (both inclusive)
(200-3) + 1 = 198 numbers.

flip the sentence to become 200+199+198+...+4+3
Add this new sentence to the question, you'll get 203+203+203+...+203

198 x 203 = 40194
40194 /2 = 20097 (have to divide cos you've made a duplicate)

For the next question , same way of doing, try it.
but to find how many numbers there are :
(400-10)/2 + 1 = 196 numbers
(reason why divide by 2 is you are skipping 1 number in between)

[JadeDry]

Eddow:

mum_sugoku:

[quote=\"JadeDry\"]@ Eddow & Pinkapple


I checked the question, it still is: 9(x to the power of ab) - ((xy) to the power of ab) - 9(y to the power of ab) - 81

I would appreciate more help if you do not mind.

Which is the simplest form?:

(4X- 8Y) or 4(X-2Y)

And why?

Thanks in advance.

If question is .... \"+\" ((xy) to the power of ab).... instead of \"-\", then solution is (x^ab -9) (y^ab +9)..

I suspect printing error in the question. If it's ....+81, then answer should be (x^ab +9) (9 - y^ab)

For question like this...Which is the simplest form?:
(4X- 8Y) or 4(X-2Y) .
If the question is asking you to FACTORISE, then correct ans is 4(x-2y).[/quote]If I am asked to simplify is the correct answer also 4(X-2y)?