(k – 16)(k + 16) ≥ 0  means positive,

if k is between 0 and 16 then (k – 16) is negative and (k + 16) is positive therefore (k – 16)(k + 16) will be negative (- ve) x (+ ve) = (-ve)
again if k is between – 16 and 0 then also (k – 16) is negative and (k + 16) is positive therefore (k – 16)(k + 16) will be negative (- ve) x (+ ve) = (-ve)
but if k is less than – 16, then (k – 16) is negative and (k + 16) is also negative therefore (k – 16)(k + 16) will be positive (- ve) x (-ve) = (+ve)
and if k is more than  16, then (k – 16) is positive and (k + 16) is also positive therefore (k – 16)(k + 16) will be positive (+ ve) x (+ve) = (+ve)

therefore k is either ≤ – 16 or ≥ 16.

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Tuesday,11^th February 2014,21:32:14

one more problem,sir, in the following sum:
Find the values of K for which the equation 2x^2+Kx+2=0 has real roots.
i did it this way:
b^2-4ac>=0
=> K^2-16>=0
=>K^2>=16
=>K>= +-4
the answer given in the book is:
K>=4 or K<= -4.
but how?

Name: Anisha Saha
School: Douglas Memorial
Class: X
 Hope you got the answer in the previous solution! All the best for your exams!

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Tuesday,11^th February 2014,21:23:23

Sir, i couldn't do the following sum:
find the positive value of K for which the equation x^2+Kx+64=0 and x^2-8x+K=0 will have real roots.

Name: Anisha Saha
School: Douglas Memorial
Class: X

 x² + kx +64 = 0
b² – 4ac ≥ 0
 k² – 256 ≥ 0
(k – 16)(k + 16)≥ 0

what is single transformation?

Ananya Sarkar
Class: 10

 WHEN A POINT IS REFLECTED MORE THAN ONCE, THE REFLECTION OF THE FINAL POINT FROM THE ORIGINAL IS KNOWN AS SINGLE TRANSFORMATION.
FOR EXAMPLE:
A point A(2,-3) is reflected on the x-axis to point B, the point B is further reflected to y-axis to point C, find the single transformation.

Here the point B will be (2, 3) and point C will be (-2, 3)
now single transformation means A to C means original point A(2,-3) and reflected point C(-2, 3), A will be reflected to C if it is reflected about the origin.
thus the single transformation is reflecting on the origin.

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 "MERRY CHRISTMAS TO YOU ALL!
I ALSO MISS YOU ALL A LOT! TAKE CARE! GOD BLESS YOU!

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Wed Dec 25 at 12:47 am

Sir, no queries. Merry Christmas to u. We all Douglas students really miss u sir. Its end of an era.

Name: saptaswa bhattacharya
Class: 10

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Mon Dec 23 at 9:19 Pm

Thank you, sir, for the help

Name: Anisha
Class: 10^th

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Sat Dec 21 at 8:41 am

Sir, i have a problem in solving the following sum:
#A circle is drawn to touch the four side of a quadrilateral PQRS.If O is the centr of the circle,prove that: angle.POQ + angle.ROS=180 degree

Name: Anisha
Class: 10^th

Construction join OW OX OY OZ, use tangent property ..congruent triangles,
angle YOQ=angleXOQ…

a + a + b + b + c + c + d + d = 360^o

2( a+ b+ c+ d) = 360^o

a + b + c + d = 180^o

(a + d) + (b + c) = 180^o

angle.POQ + angle.ROS=180^o

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I WILL ALSO MISS YOU ALL DEAR! GOD BLESS YOU ALL AND BEST OF LUCK FOR YOUR FUTURE!

********************************************************************************** 29^th November 2003: 1:03 am
 " From the 1st day in DMHSS, i have heard about u from many students as they all get afraid by your name. But i used to think that when i haven't done any mistake then y should i get afraid? Slowly we got well acquainted with each other, spcly in class X. I started enjoying your class. The way you taught is very impressive. I still remember the words, "look at the board, don't write anythng". Moreover, how can i forget the innovative punishments you used to give. The days were really memorable. 7 months passed so fast. It was only you who used to summon me 1st for the "hair-cut". But now sir, no one will summon me lyk that. No one will give punishments of 50 or 100 sums. Last year, during the annual concert, when i got hurt, it was only u and babu sir, who took me to the B.N. Bose hospital. It was u who looked after me at that time when my parents were not with me. I don't know about others sir, but i will miss you. i will miss you a lot. I wish you a very good luck and forgive me for all my mistakes. You will always be in our heart! We salute you! Good bye sir! "

Name: Adrish
Class: X-B

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23^rd November 2013 ; 10:04 p.m.

 " goodbye sir!! we will all miss u..... ."
Name: shilpi  jhunjhunwala
Class: 11
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  9^th  Sunday; 20th October 2013 : 22:03:54.

" A short message fr u... I dont know abt others bt it is going to be very tough fr me to adjust with a new teacher...i will miss ur intresting punishments, i will miss ur scoldings and last bt nt the least i will miss u as wll as ur teachings..I wish u all the vry best fr ur new school nd dmhss can never frget u.. :-)."
Name: Suyeshna Laha

Class: X
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9^th Oct 2013;06:10:50 p.m.

"Fw mnts bak vztd ur pg each wrds in those fw lynes wrttn 4 ur drst stdnts r equally inspiring as ur carefl mntoring & broad guidnce 2 all of thm till date, though ur altime presence will b missing in thm aftr fw days bt they wl nvr actually miss u bcz through ur tchng u r alws prsnt in thr hrts.. guiding & showing thm ryt path of honesty
stdnts & each & evry! associated wth St Stphns r going 2 b xtrmly luky 2 hv u amng thm.
I nvy thm vry much......."

Pausali Mukherjee