Question

   in the  first line -2x is there in numerator. In next step 2 is no thers. How? 

please solve 3&4 questions

 chq. paid entry

sum of series 1+(1+4)+(1+4+7)+(1+4+7+10)+........

Find the summation of the first n term 1+(1+4)+(1+4+7)+(1+4+7+10)+....

• What your gst 
  

in the figure, ba perpendicular to ac, de perpendicular to df such that ba = de and bf = ec. show that triangle abc is congruent to triangle def.