Question

ex 31 si 32 plizz
va roooog

Answer 1

31. a) x+y+24=48 => x+y+z= 48-24=24
           15+2z+2y+2x=15+ 2(z+y+x)= 15+ 2*24=15+48=63
       b)3x+3y+23=65 => 3x+3y=42 => 3(x+y)=42 => x+y=42/3=14
         2x+2y+27= 2(x+y) +27= 2*14 +27=28+27=55
       c)x+3y+2z+16=50 => x+3y+2z=50-16=34
           2x+6y+4z+12= 2(x+3y+2z) +12= 2*34+12= 68+12=80
   32. a) 1+2+3+...+29= 29*30 /2= 29*15= 435
         b)10+20+30+...+200= 10*(1+2+3+...+20)= 10* 20*21/2= 10*10*21=2100
       c)5+10+15+...+125= 5*(1+2+3+...+25)= 5* 25*26/2= 5*25*13=1625
       d) 19+20+21+...+39= S39-S18=39*40/2 - 18*19/2= 39*20 - 9*19= 780-171=609