Hello Everybody!

YA!HA!

EXam!Is very important.SO I do rev. todat

bored. tired.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

The easiest F.:

1+2+3+4+...+1000=(1+1000)*1000/2=1001*500=500500

Today ,i destory class num.2 ' plastic bag.wakakaka.

ax2次方+bx+c=0

x=-b±√b2次方-4ac over2a

e.g:3x2次方+5x+7=0

x=-5±√5*5-4*3*7 over 6

 =-5±√25-84 over 6

 =-5±√-59 over6

 =-5±√59i over6(i2次方=-1)

1*1+2*2+3*3+4*4+...+100*100=n(n+1)(2n+1)/6=100(100+1)(2*100+1)/6=100*101*201/6=10100*201=2030100/6=33835