O-Level Additional Math

[jtoh]

red rose:

jtoh:

Hi red rose, I only managed to get x = -2 too. Could the answer sheet be wrong? Is this question from a workbook?

Nope. It's from a Sec 2 IP school revision worksheet. Thanks for trying anyway. The curious thing is, +2 works too when substituted into the equation.

Hmm... are we approaching the question wrongly from our archaic math training? Could your dd get the answer? I'll ask my dd to try it later. Is this the school's worksheet?

[red rose]

jtoh:

red rose:

[quote=\"jtoh\"]Hi red rose, I only managed to get x = -2 too. Could the answer sheet be wrong? Is this question from a workbook?

Nope. It's from a Sec 2 IP school revision worksheet. Thanks for trying anyway. The curious thing is, +2 works too when substituted into the equation.

Hmm... are we approaching the question wrongly from our archaic math training? Could your dd get the answer? I'll ask my dd to try it later. Is this the school's worksheet?[/quote]My dd got -2, which was why she approached me to see if I had another approach.

[jtoh]

Me suspects the answer key could be wrong. I've PM you.

[rylee]

red rose:

Need help to solve this.


x - 2/x + 3 = 2x^2 + x - 10/x^2 + 6x + 9

I only managed to get x = -2, but the answer key says the answer should be x = 2 or x = -2. Please advise.

Thank you in advance.

Hi red rose,

The answer is x=+2 or -2

Working as follow:-

(x-2)/(x+3)=(2x^2+x-10)/(x+3)^2

(x-2)(x+3)=2x^2+x-10

X^2-2x+3x-6=2x^2+x-10
X^2+x-6=2x^2+x-10
x^2-6 =2x^2-10
x^2=4
x=+2 or -2

Regards.

[red rose]

rylee:

red rose:

Need help to solve this.


x - 2/x + 3 = 2x^2 + x - 10/x^2 + 6x + 9

I only managed to get x = -2, but the answer key says the answer should be x = 2 or x = -2. Please advise.

Thank you in advance.

Hi red rose,

The answer is x=+2 or -2

Working as follow:-

(x-2)/(x+3)=(2x^2+x-10)/(x+3)^2

(x-2)(x+3)=2x^2+x-10

X^2-2x+3x-6=2x^2+x-10
X^2+x-6=2x^2+x-10
x^2-6 =2x^2-10
x^2=4
x=+2 or -2

Regards.

:thankyou: Greatly appreciated!

[jtoh]

Thanks rylee.

[blitz]

URGENT


Need help to solve this.

If X^2+Y^2=8 and (X+Y)=5 Find the value of 4XY

and

Given that (a/3)=Square root of ((b+1)/(b-1))
express b in terms of a
Find b if a=7

Thank you in advance.

[FrekiWang]

blitz:

URGENT


Need help to solve this.

If X^2+Y^2=8 and (X+Y)=5 Find the value of 4XY

and

Given that (a/3)=Square root of ((b+1)/(b-1))
express b in terms of a
Find b if a=7

Thank you in advance.

Both questions are very standard, you may have to revise your work carefully since you have difficulties in them.
1.
X+Y=5
(X+Y)^2=25
X^2+2XY+Y^2=25
given X^2+Y^2=8
2XY=25-8=17
4XY=34
(I do not like the question as X and Y are not real numbers)

2.
Square both sides, we have
a^2 / 9 = (b+1) / (b-1)
Cross multiplying them, we have
(a^2)b - (a^2) = 9b + 9
(a^2 - 9)b = 9 + a^2
b = (9+a^2) / (a^2 - 9)
if a=7,
b=(9+49)/(49-9)=58/40=29/20 (or 1.45)

[blitz]

Thanks FrekiWang

[Andrew Lee]

liketoeat:

Thanks FrekiWang, it's a sec 1 qn.

Hi, can help me solve this question:

a. 7(x+3)-(4x-5)=5-(3x+6)

The HCF of two numbers is 1 and the LCM of these numbers is 91, what are the numbers? :roll:

b.(12y-4)/6 = (7y-4)/5

The product of the ages of a group of teenagers (13-19 yr old) is 4590 yrs, Find --
(i) the numbers of teenagers in the group :roll:
(ii) the sum of their ages :roll: