Lower Secondary Mathematics

[albertong]

Mr Tan’s monthly savings (S) is directly proportional to the square root of his monthly income (I). His income in January and February 2011 is $3600 and $2500 respectively. His savings in January is $80 more than in February. Find the amount he saved in January 2011.

[jieheng]

Mr Tan’s monthly savings (S) is directly proportional to the square root of his monthly income (I). His income in January and February 2011 is $3600 and $2500 respectively. His savings in January is $80 more than in February. Find the amount he saved in January 2011.

S ∝ √I

S=k√I

January's savings ,
S(J)=k√3600 =60k

February's savings,
S(F)=k√2500 =50k

His savings in January is $80 more than in February,

S(J) - S(F) = 80
60k - 50k = 80
10k = 80
k = 8

S = 8√I

S(J) = 8√3600 = 480

the amount he saved in January 2011 is $480

[albertong]

Thanks!!

[strawberrycupcakes]

thanks too

[Ovencookies]

Hi my sons maths is quite weak what do your think is the best thing to do at this time when his o levels are coming soon ?

[she0407]

Algebra Q

Subtract 18x³ - 8x – 12 from 6x ( 2x² - 3)



My answer is different from the teacher, so need a third party (experts here) to prove me wrong.

Thanks.

[ngl2010]

6x ( 2x² - 3 ) - ( 18x³ - 8x – 12 )
= ( 12x³ - 18x ) - ( 18x³ - 8x – 12 )
= 12x³ - 18x - 18x³ + 8x + 12
= - 6x³ - 10x + 12

Is the answer same as yours or your teacher's?

[she0407]

Mine.

[Gemini11]

Ur teachers answer maybe
- 2(3x^3 + 5x-6)
After simplifying?

[Michaelia0816]

Need help with coordinate question:

Diagram:
http://t.co/6BaWYM3Fka

Questions:
(a) The coordinates of A and B are ____ and ____ respectively.
(c) The area of Triangle BOC is ____ units
(d) AB cuts the line x = 0 at ____.
(f) The line AB passes through (p,-1), the value of p is ___.