rut gon bieu thuc
(a+b-c)^2 - (a-c)^2- 2ab+ 2bc
NH
Những câu hỏi liên quan
cho a,b,c khac nhau doi mot va 1/a+1/b+1/c=0.rut gon cac bieu thuc
N=bc/a^2+2bc+CA/B^2+2AC+AB/C^2+2AB
ai tra loi nhanh cau nay minh tich ngay nguoi do
de bai rut gon bieu thuc
\(\left(a+b-c\right)^2-\left(a-c\right)^2-2ab+2bc\)
\(\left(a+b-c\right)^2-\left(a-c\right)^2-2ab+2bc\)
\(=a^2+b^2+c^2+2ab-2ac-2bc-a^2+2ac-c^2-2ab+2bc\)
\(=b^2\)
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Rut gon cac bieu thuc sau:
2(x-y).(x+y)+(x-y)^2+(x+y)^2
(2x-3).(4x^2+6x+9) -(54+8x)
(3x+y).(9x^2-3xy+y^2)-(3x-y).(9x^2+3xy+y^2)
(a +b +c)^2-(a-c)^2-2ab+2bc
\(a,\)\(2\left(x-y\right)\left(x+y\right)+\left(x-y\right)^2+\left(x+y\right)^2.\)
\(=\left[\left(x-y\right)+\left(x+y\right)\right]^2=\left(x-y+x+y\right)^2=x^2\)
\(b,\)\(\left(2x-3\right)\left(4x^2+6x+9\right)-\left(54+8x\right)\)
\(=8x^2-27-54-8x=8x^2-8x-81\)
\(c,\)\(\left(3x+y\right)\left(9x^2-3xy+y^2\right)-\left(3x-y\right)\left(9x^2+3xy+y^2\right)\)
\(=27x^3+y^3-\left(27x^3-y^3\right)=2y^3\)
\(d,\)\(\left(a+b+c\right)^2-\left(a-c\right)^2-2ab+2bc\)
\(=a^2+b^2+c^2+2ab+2bc+2ac-a^2+2ac-c^2-2ab+2bc\)
\(=b^2+4bc+4ac\)
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cho \(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=0\) va a,b,c khac 0. Rut gon bieu thuc N=\(\frac{1}{a^2+2ab}+\frac{1}{b^2+2ca}+\frac{1}{c^2+2ab}\)
Rut gon bieu thuc: (a-b+c)^2+2(a-b+c)(b-c)+(b-c)^2
Dùng hằng đẳng thức A2 + 2AB + B2 = ( A + B)2 :
Ta được ... = (a-b+c+b-c)2 = a2
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rut gon bieu thuc
(a+b-c)2+(a-b+c)2-2(b-c)2
(a+b-c)^2 + (a-b+c)^2 - 2(b-c)^2
= (a + b - c)^2 - (b - c)^2 + (a - b + c)^2 - (b - c)^2
= (a + b - c + b - c)(a + b - c - b + c) + (a - b + c - b + c)(a - b + c + b - c)
= a^2 + a^2
= 2.a^2
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Rut gon bieu thuc : (a+b-c)2 + (a-b+c)2 -2(b-c)2
Ta có : (a + b - c)2 + (a - b + c)2 - 2(b - c)2
= a² + b² + c² + 2ab - 2bc - 2ca + a² + b² + c² + 2ca - 2ab - 2bc - 2(b2 - 2bc + c2)
= a² + b² + c² + 2ab - 2bc - 2ca + a² + b² + c² + 2ca - 2ab - 2bc - b2 + 2bc - c2
= 2a2 + b2 + c2 - 2bc
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rut gon bieu thuc
(a+b-c)2+(a-b-c)2+(b-c-a)2+(c-b-a)2
(a + b + c)^2 + (a - b - c)^2 +( b - c - a) ^2 + (c - a - b)^2
= (a + b + c)^2 + (a + b - c)^2 + (a - b - c)^2 + (a - b + c)^2
= (a + b)^2 + 2c(a + b) + c^2 + (a + b)^2 - 2c(a + b) + c^2 +
(a - b)^2 - 2c(a - b) + c^2 + (a - b)^2 + 2c(a - b) +c^2
= 2(a + b)^2 + 2c^2 + 2(a - b)^2 + 2c^2
= 2[(a + b)^2 + (a - b)^2] + 4c^2
=2(2a^2 + 2b^2) + 4c^2
= 4(a^2 + b^2 + c^2)
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rut gon bieu thuc
(-a-b+c) - (-a-b-c)
= ( -a ) -b +c + a +b +c
=[ ( -a ) + a ] + b - b + c + c
= 0 + ( b-b ) + ( c+c )
=0+0+ 2x
=2x
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(-a-b+c) - (-a-b-c)
=-a-b+c+a+b+c
=(a-a)+(b-b)+(c+c)
=0+0+c.2
=c2
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