Question

Se stie ca a+b+c=23 si x=9. Calculati:
3147-10*x-(100*a+100*b+100*c)=

Calculati, folosind factorul comun:
2+4+6+8+10+12=
13*17+13*25-42*11-2*41=

Calculati:
a) a*b+a*c stiind ca b+c=157 si a=6
b) a*b - a*c stiind ca a=25 si b-c=147
c) a*b+a*c+a*d stiind ca a=14 si b+c+d=59

Gasiti si scoateti un factor comun, cand calculati urmatoarele sume:
a) 5+10+15+20+....+1000
b) 8+16+24+32+...+4000
c) 11+22+33+44+...+7700

SI VA ROG SA SCRIETI SI CUM ATI REZOLVAT, NU NUMAI REZULTATUL!

*fiecare exercitiu 10 puncte*
10p+10p+10p=30p

Multumesc!

Answer 1

1)a+b+c=23;x=9
3147-10*x-(100*a+100*b+100*c)=3147-10*9-100(a+b+c)=3147-90-100*23=3147-90-2300=787

2)•2+4+6+8+10+12=2*(1+2+3+4+5+6)=2*21=42
•13*17+13*25-42*11-2*41=13*(17+25)-462-82=546-462-82=2

3)•a)b+c=157;a=6
a*b+a*c=a*(b+c)=6*157=942
•b)a=25;b-c=147
a*b-a*c=a*(b-c)=25*147=3675
•c)a=14;b+c+d=59
a*b+a*c+a*d=a*(b+c+d)=14*59=826

4)•a)5+10+15+20+...+1000=5*(1+2+3+4+...+200)=5*(200*201):2=5*(100*201)=5*20100=100500
•b)8+16+32+...+4000=8(1+2+3+4+...+500)=8*(500*501):2=8*(250*501)=8*125250=1002000
•c)11+22+33+44+...+7700=11(1+2+3+4+...700)=11*(700*701):2=11*(350*701)=2698850.

Sper ca ti-am fost de ajutor... merit coroană?