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I
30 tháng 8 2015
a+b+c=0<=>a^2+b^2+c^2+2ab+2bc+2ca=0
<=>a^2+b^2+b^c=-2ab-2bc-2ca
<=>(a^2+b^2+c^2)^2=4a^2b^2+4b^2c^2+4c^2a^2+8abc(a+b+c)
<=>(a^2+b^2+c^2)^2=4a^2b^2+4b^2c^2+4c^2a^2(vì a+b+c=0)(1)
(a^2+b^2+c^2)^2=4a^2b^2+4b^2c^2+4c^2a^2
<=>a^4+b^4+c^4+2a^2b^2+2b^2c^2+2c^2a^2=4a^2b^2+4b^2c^2+4c^2a^2
<=>a^4+b^4+c^4=2a^2b^2+2b^2c^2+2c^2a^2
<=>2(a^4+b^4+c^4)=4a^2b^2+4b^2c^2+4c^2a^2(2)
Từ (1) và (2)=>Đccm
L
1
CE
2
17 tháng 10 2016
y^6-x^6=(y^3-x^3)(y^3+x^3)=(y-x)(y^2+xy+x^2)(x+y)(x^2-xy+y^2)
NH
17 tháng 10 2016
5y^6-5x^6
=5(y^6-x^6)
=5(y^4+x^4)(y^4-x^4)
=5(y^4+x^4)(y^2+x^2)(y^2-x^2)
=5(y^4+x^4)(y^2+x^2)(y-x)(y+x)
19 tháng 12 2021
\(\Leftrightarrow\left(x+3\right)\left(10-5x\right)=0\)
=>x=-3 hoặc x=5
200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000X20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
=4000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 x 200000000000000000000000000000000000000000000000000000000000000 = 4000000000000000000000000000000000000000000000000000000000000