khó quá

 0,187 ;0,198;0,32;0,321;0,4

3+3=6 

chúc bn may mắn

GIÚP MÌNH ĐIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIMẤY BẠN UIIIIIIIIIIIIII 

..

\(\left(a+b+c\right)^2=a^2+b^2+c^2+2ab+2bc+2ca=\)

\(=\left(a^2+b^2+c^2\right)+2\left(ab+bc+ca\right)=13^2=169\)

\(\Rightarrow85+2\left(ab+bc+ca\right)=169\Rightarrow ab+bc+ca=42\)

1+1-1=XX+X

(a +b+c)² = a² + b² + c² + 2ab + 2ac + 2bc ( hằng đẳng thức mở rộng )

13² = 85 + 2 ( ab + bc +ca )

\(\Rightarrow\)ab + bc + ca = (169 - 85) :2 = 42

tổng 3 số là: 180x3=540

số thứ 1: 3 phần

số thứ 2: 2 phần

số thứ 3:5 phần

số thứ 1 là:

              540:(3+2+5)x3=162

                                   ĐS: 162

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