## Rangpur Higher Secondary 2011/7

Problem for Higher Secondary Group from Divisional Mathematical Olympiad will be solved here.
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BdMO
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Joined: Tue Jan 18, 2011 1:31 pm

### Rangpur Higher Secondary 2011/7

Problem 7:
If \$A + B =1\$, \$B + C = 2\$, \$C + D = 3\$, ..., \$X + Y = 25\$, \$Y + Z = 26\$, find \$A – Z\$.

leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: Rangpur Higher Secondary 2011/7

\$A+B=1\$
\$B+C=2\$
\$C+D=3\$
. . .
. . .
\$X+Y=25\$
\$Y+Z=26\$
( biog ) we get
\$A-Z\$=\$1-2-3-. . . .-25-26\$
so \$A-Z=1-(1+2+. . . .+25+26)+1\$
the result is \$-349\$.
Ibtehaz Shawon
BRAC University.

long way to go .....

Mehfuj Zahir
Posts: 78
Joined: Thu Jan 20, 2011 10:46 am

### Re: Rangpur Higher Secondary 2011/7

A-C+C-D=A-D
(A-D)+(D+E)=A-E
A-E+E+F=A+F
DO IT CONSECUTIVELY AND GET THE ANS -13

Tahmid Hasan
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Joined: Thu Dec 09, 2010 5:34 pm

### Re: Rangpur Higher Secondary 2011/7

let's name the eqs 1,2,3,......25.then \$1-2+3......\$
get the ans
বড় ভালবাসি তোমায়,মা

leonardo shawon
Posts: 169
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Location: Dhaka

### Re: Rangpur Higher Secondary 2011/7

Mehfuj Zahir wrote:Your formula is uncorrect.(A+B)-(B+C)=A-C
A-C+C-D=A-D
(A-D)+(D+E)=A-E
A-E+E+F=A+F
DO IT CONSECUTIVELY AND GET THE ANS -13
u misunderstood (may be)[\B]
thats a sequence from A to Z.

Mehfuj Zahir
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Joined: Thu Jan 20, 2011 10:46 am

### Re: Rangpur Higher Secondary 2011/7

By doing it at last u get A-z=-13

leonardo shawon
Posts: 169
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Location: Dhaka

### Re: Rangpur Higher Secondary 2011/7

the Left side of Equation is \$A-z\$ ok? So the right side is
\$1-2-3-4. . . . . . .-25-26\$
=\$1-(2+3+4+5. . . .+25+26)\$
=\$1-(1+2+3+4. . . .+25+26)+1\$
=\$2-(27*13)\$
=\$2-351\$
=\$-349\$
... There are 26 equations. When we substract 26 equation at a time the first and last variables will left on the left side and one right side only the value of first equation will have positive sign.
or use a CALCULATOR.
Ibtehaz Shawon
BRAC University.

long way to go .....

Mehfuj Zahir
Posts: 78
Joined: Thu Jan 20, 2011 10:46 am

### Re: Rangpur Higher Secondary 2011/7

it will like 1-2+3-4+5

leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: Rangpur Higher Secondary 2011/7

i told to substract all the equation.
Ibtehaz Shawon
BRAC University.

long way to go .....

Mehfuj Zahir
Posts: 78
Joined: Thu Jan 20, 2011 10:46 am

### Re: Rangpur Higher Secondary 2011/7

If u dp it u don't have A-z