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#51 Re: Exercises » Play with numbers » 2009-03-29 18:27:43
#5
now dis is a good one ...
A sequence of positive real numbers is defined as:
Y(0) = 1
Y(n+2) = 2*Y(n) - Y(n+1), for n = 0, 1, 2, ...
What is the value of Y(2007)?
#52 Re: Exercises » Counting Problems » 2009-03-29 17:20:33
well i think franklin is correct ... i didn't notice the "followed by" constraint ...
#53 Re: Exercises » Play with numbers » 2009-03-26 23:32:40
A * B * C = B * G * E = D * E * F
all the letters have 1-to-1 mapping with single digit numbers.
find the value of G
#54 Re: Exercises » Play with numbers » 2009-03-26 23:17:07
A number of 9 digits has the following properties:
The number comprising the leftmost two digits is divisible by 2, that comprising the leftmost three digits is divisible by 3, the leftmost four by 4, the leftmost five by 5, and so on for the nine digits of the number i.e. the number formed from the first n digits is divisible by n, 2<=n<=9.
Each digit in the number is different i.e. no digits are repeated.
The digit 0 does not occur in the number i.e. it is comprised only of the digits 1-9 in some order.
Find the number.
#55 Re: Exercises » Play with numbers » 2009-03-26 23:15:37
et N = 1111...(upto 3^x digits) ... where x ∈ N
prove that N is divisible by 3^x
#56 Exercises » Play with numbers » 2009-03-26 23:06:45
- smiyc86
- Replies: 39
A= 1999^1999
B = sum of digits of A
C = sum of digits of B
D = sum of digits of C
find the sum of digits of D
#57 Re: Puzzles and Games » Complete the series.... » 2009-03-26 22:54:47
typo 215 =6^3 -1
#58 Re: Puzzles and Games » Complete the series.... » 2009-03-26 22:52:43
215 = 5^3-1
try this ...
0,2,3,4,5,5,7,6,6,7,11,7,13,11,8,8,17,8,19,9,10,_,_,_
#59 Re: Puzzles and Games » Connotations. » 2009-03-26 22:49:28
1. murderer
2. ICcubes
3. fear
#60 Re: Exercises » Counting Problems » 2009-03-26 22:36:55
26c2 * 10c3 * 5!
#62 Re: Help Me ! » smilarity » 2009-03-26 22:33:18
pleasure
#63 Re: Help Me ! » quadratic formula problems? D: » 2009-03-26 17:05:18
for the last one .....
let $5 be increased x times ... then 30x students are reduced ...
the equation can be formed as:
(20 + 5x)(300 - 30x) = 7200
=> (x-10)(x+4) + 48 = 0
=> x = 2,4
so the prices that will generate $7200 sales will be : $30, $40
#64 Re: Help Me ! » quadratic formula problems? D: » 2009-03-26 16:50:43
for the 2nd one .... if u visualise , the height of the box = side of the square pieces which are cut out = 10 cm
hence the base area of the box = 120 cm^2
now as the base of the box will also be a square, hence the side of the base of the box = √120 = 2√30
the original side of the tin plate = 2√30 + 10 cm ....
#65 Re: Help Me ! » quadratic formula problems? D: » 2009-03-26 16:46:02
Hey im having trouble with these problems, and i think were supposed to use the quadratic formula somewhere? not sure D: ..
1. The hypotenuse of a right angled triangle is 15 cm. The sum of the other two sides is 21 cm. Find the lengths of the other two sides.
2. a lidless box is to be constructed from a square peice of tin by cutting a 10 cm square from each corner and bending up the sides for the box. If the volume of the box is 1200cm3, find the dimentions of the original sheet of tin.
LASTLY,
3.computer software programs are sold to students for $20 each. 300 students are willing to buy them at this price. for each $5 increase in price, there are 30 fewer students wiling to buy the software. what price of software will generate $7200 in sales?THANKS(:
1. try to learn few pythagorean triplets... the most basic one is 3:4:5 ... now if 3:4:5 is a pyth. triplet then 3x:4x:5x is also a triplet .... now for this triplet the hyp:(sum of the other two sides) = 5x:7x =
in this case it is true .... 15:21 = 5*3:7*3
so the other two sides are 3*3 and 4*3 = 9,12
#66 Re: Help Me ! » smilarity » 2009-03-26 16:38:12
as ganesh has already provided the diagram ... am providing the solution ...
AE/AB = EC/BC .... bisector theorem ...
from this we get ...
EC/AE = 2/3
=> AC/AE = 5/3 ... AC = AE + EC
now, AEF ~ ACD
hence, CD/EF = AC/AE
CD = 4
#67 Re: Help Me ! » factoring » 2009-03-26 16:25:13
yeah, i guess thats my answer then, lmao
nooo real roots(:
always check for b^2 - 4ac in the equation ax^2+bx+c = 0
when b^2 - 4ac < 0 u wont get real roots ....
= 0 the roots will be real and equal ...
> 0 the roots will be real and unequal ...
even for b^2 - 4ac > 0 ,
if it is a square of a rational number, the roots will be rational
if it is not, the roots will be irrational.
#68 Re: Help Me ! » finding the missing side of a triangle » 2009-03-26 16:11:09
On a 30-60-90 triangle, the longest side is always twice as big as the shortest side.
That fact, along with Pythagoras and the side length you know, should let you find out everything about the triangle.
to add to that ... the sides of the triangle will be in the ratio (side opp to 30 deg):(side opp to 60 deg):side opp to 90 deg) = 1:√3:2 ....
#69 Re: Introductions » Hey all... » 2009-03-22 16:39:05
hi again to awl ....
@lightning ... i cudn't figure out the 'R' though
#70 Re: Help Me ! » help please » 2009-03-19 21:12:22
This is quite a well-known puzzle.
To get from one step to the next, say what you see.
nice hint ... gotcha
#71 Introductions » Hey all... » 2009-03-19 21:10:29
- smiyc86
- Replies: 5
Hi there peeps am soumya am from from India ... maths has been an important subject of study in our part of world ... and it has entertained me all my life and it will keep on doing so ... ....
#72 Help Me ! » Probability » 2009-03-19 20:49:51
- smiyc86
- Replies: 1
I know the formula for this but i need a proof of how to arrive at this formula ... can neone help me ...
There are 'n' no. of balls marked 1 to n .... and 'n' no. of boxes marked 1 to n ..... each box can hold only one ball and every ball should go into a box ....
what is the no. of ways in which we can place the balls in the boxes such that no ball goes into its same numbered box...
the answer is
n! ( 1/2! - 1/3! + 1/4! ... 1/n!)
Post the solution