Question

[Hà Việt Anh]

CAO NHÂN NÀO GIÚP EM TỜ ĐỀ KHÓ QUÁ Ạ

Answer 1

[bui van trong]

Cau 2

1. TA CO :\(\frac{1}{A}\)+\(\frac{1}{B}\)+\(\frac{1}{c}\)=\(\frac{1}{2019}\)
2. <=>\(\frac{1}{a}\)+\(\frac{1}{b}\)+\(\frac{1}{c}\)=\(\frac{1}{a+b+c}\)
3. <=>(\(\frac{1}{a}\)+\(\frac{1}{b}\))+(\(\frac{1}{c}\)-\(\frac{1}{a+b+c}\)=0
4. <=>\(\frac{a+b}{ab}\)+\(\frac{a+b}{c\left(a+b+c\right)}\)=0
5. <=>(a+b)(\(\frac{1}{ab}\)+\(\frac{1}{c\left(a+b+c\right)}\))=0
6. <=>\(\frac{\left(a+b\right)\left(b+c\right)\left(a+c\right)}{abc\left(a+b+c\right)}\)=0
7. <=>\(\left(a+b\right)\left(b+c\right)\left(a+c\right)=0\)
8.  
9. gia su\(\left(a+b\right)=0\)=>c=2016 khi do
10. \(\frac{a^{2019}+b^{2019}}{\left(ab\right)^{2019}}+\frac{1}{c^{2019}}=\frac{1}{c^{2019}}=\frac{1}{a^{2019}+b^{2019+c^{2019}}}\)
11. cac truong hop kia tuong tu
12.  

Answer 2

[bui van trong]

1. \(\left(a+b+c\right)^2=a^2+b^2+c^2\)
2. <=>\(a^2+b^2+c^2+2\left(ab+bc+ac\right)=a^2+b^2+c^2\)
3. ,=>\(2\left(ab+bc+ac\right)=0\)
4. <=>\(ab+bc+ac=0\)
5. <=>\(ab=-\left(bc+ac\right),bc=-\left(ab+ac\right),ac=-\left(ab+bc\right)\)
6. voi \(ab=-\left(bc+ac\right)\)=>\(c^2+2ab=c^2+ab-bc-ac=\left(a-c\right)\left(b-c\right)\)
7. tuong tu \(a^2+2bc=\left(a-c\right)\left(a-b\right)\)
8.               \(b^2+2ac=-\left(b-c\right)\left(a-b\right)\)
9. =>\(P=\frac{a^2}{\left(a-c\right)\left(a-b\right)}-\frac{b^2}{\left(b-c\right)\left(a-b\right)}+\frac{c^2}{\left(a-c\right)\left(b-c\right)}\)\(=\frac{a^2\left(b-c\right)-b^2\left(a-c\right)+c^2\left(a-b\right)}{\left(a-b\right)\left(a-c\right)\left(b-c\right)}=1\)