Question

[Bá Ngọc Minh Trang]

tìm x E Z, biết:

c) (-1)+3+(-5)+7+...+x = 600

d) 2+(-4)+6+(-8)+...+(-x) = -2000

Mik đag cần gấp!

Answer 1

[Võ Nhật Cường]

Ta có cttt : (\(\frac{x-3}{4}\)+1 )(\(\frac{x+3}{2}\)-\(\frac{x-1}{2}\))=600

<=>(\(\frac{x-3}{4}\)+1)2=600

<=>\(\frac{x-3}{4}\)+1=300

<=>\(\frac{x-3}{4}\)=299

<=>x-3=1196

<=>x=1199

Answer 2

[Võ Nhật Cường]

Ta có cttt ;(\(\frac{x-4}{4}\)+1)(\(\frac{x}{2}\)-\(\frac{x+4}{2}\))=-2000

<=>(\(\frac{x-4}{4}\)+1)-2=-2000

<=>\(\frac{x-4}{4}\)+1=1000

<=>\(\frac{x-4}{4}\)=999

<=>x-4=3996

<=>x=4000