855

tk mk nha

mk tk lại

mk hứa

x^2+y^2+z^2= xy+yz+zx 

=> 2( x^2+y^2+z^2)= 2( xy+xz+yz)

=> 2x^2+2y^2+2z^2= 2xy+2xz+2yz

=> x^2+x^2+y^2+y^2+z^2+z^2= 2xy+2xz+2yz

=> x^2+x^2+y^2+y^2+z^2+z^2-2xy-2xz-2yz= 0

=> x^2-2xy+y^2+y^2-2yz+z^2+z^2-2zx+x^2=0

=> (x-y)^2+(y-z)^2+(z-x)^2 =0

ta thấy (x-y)^2>= 0

(z-x)^2>=0

(y-z)^2>=0

nên (x-y)^2+(y-z)^2+(z-x)^2 >=0

dấu bằng xảy ra khi và chỉ khi

x-y=0 => x=y

y-z=0=> y=z

z-x=0 => z=x

=> x=y=z

=>5x=-60

=>x=-12

Ai tích mk mk sẽ tích lại

Ta có \(0,6=\frac{3}{5}\)

vậy số lớn là 12:(5-3).5=30

số lớn là 30-12=18

70,81,18,92,29

Vậy có 5 số

vì : 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20 =  210 nên x là 20

k mik nha

= qua dai dong

AD định lý Bơ-du: phép chia đa thức f(x) cho x-a là f(a).

   Thay x=1 vào đa thức f(x)=> KQ tìm được chính là số dư cần tìm

KHI KO BIẾT TÍNH

15/ When I got up, it _________.

A. rains B. rained C. is raining D. was raining

16/ Mrs. Thu _________ the newspaper while her husband was watching T.V. A. was reading B. is reading C. reads D. read

17/ Mr. Quang fell over while he _________ basketball.

A. was playing B. is playing C. played D. plays

18/ When I came home, everybody _________ the television.

A. watched B. were watching C. was watching D. is watching

19/ My father _________ out when my sister arrived at the zoo .

A. goes B. have gone C. has gone D. had gone

20/ Alice _________ a Vietnamese person until he met Nam.

A. had never met B. have never met C. never met D. never have met