Question

a) 1+3+5+......+49=
b) 5+6+7+......+81=
c) 317+318+319+.......+400=
d) 15+16+17+.......+70=
e) 1+3+5+......+213=
f) 1+3+5+......+127= Dau coroana!! Va roggg ajutorrrr

Answer 1

a) (1+2+3+...+49)-(2+4+6+...+38)=49•50:2-2•19•20:2=49•25-19•20=1225-360=865
b) 81•82:2-(1+2+3+4)=81•41-4•5:2=3321-10=3311
c)400•401:2-(1+2+...+316)=401•200-316•317:2=80200-317•158=80200-50086=30114
d)70•71:2-14•15:2=71•35-15•4=2485-60=2425
e)213•214:2-2(1+2+...+106)=213•107-2•106•107:2=107(213-106)=107•107=107^2
f)127•128:2-2•63•64:2=127•64-63•64=64(127-63)=64•64=64^2