Bài 12*.Viết các biểu thức sau dưới dạng tổng của 2 bình phương
1) \(x^2-4x+5+y^2+2y\)
2) \(2a^2+2ab-2ax+x^2+b^2\)
3) \(x^2-2x+y^2+6y+10\)
4) \(2x^2+y^2-2xy+10x+25\)
5) \(a^2+2ab+5b^2+4b+1\)
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CH
Cô Hoàng Huyền
Admin
VIP
4 tháng 7 2017
a) \(x^2-4x+5+y^2+2y=\left(x^2-4x+4\right)+\left(y^2+2y+1\right)\)
\(=\left(x-2\right)^2+\left(y+1\right)^2\)
b) \(2x^2+y^2-2xy+10x+25=\left(x^2+10x+25\right)+\left(x^2-2xy+y^2\right)\)
\(=\left(x+5\right)^2+\left(x-y\right)^2\)
c) \(2x^2+2y^2=\left(x^2-2xy+y^2\right)+\left(x^2+2xy+y^2\right)=\left(x-y\right)^2+\left(x+y\right)^2\)
1 tháng 7 2016
\(a.x^2-4x+4+y^2+2y+1\)
\(=\left(x-2\right)^2+\left(y+1\right)^2\)
1 tháng 7 2016
\(b.x^2+10x+25+x^2-2xy+y^2\)
\(=\left(x+5\right)^2+\left(x-y\right)^2\)
4 tháng 8 2017
a)x2-4x+5+y2+2y=x2-4x+4+y2+2y+1=(x-2)2+(y+1)2
b)2x2+y2-2xy+10x+25=x2-2xy+y2+x2+10x+25=(X+Y)2+(X+5)2
c)a2+2ab+5b2+4b+1=a2+2ab+b2+4b2+4b+1=(a+b)2+(2b+1)2
d)2x2+2b2+4x+4b+4=2x2+4x+2+2b2+4b+2=(\(\sqrt{2}x+\sqrt{2}\))2+(\(\sqrt{2}b+\sqrt{2}\))2
e)X4+13-6x2+4y+y2=x4-6x2+9+y2+4y+4=(x2-3)2+(y+2)2
f)-6x+9x2-8y+4y+y2+5= 9x2-6x+1+4y2-8y+4= (3x-1)2+(2y-2)2
24 tháng 8 2021
a: Ta có: \(\left(x+3\right)\left(x+4\right)\left(x+5\right)\left(x+6\right)+1\)
\(=\left(x^2+9x+18\right)\left(x^2+9x+20\right)+1\)
\(=\left(x^2+9x\right)^2+38\left(x^2+9x\right)+360+1\)
\(=\left(x^2+9x\right)^2+2\cdot\left(x^2+9x\right)\cdot19+19^2\)
\(=\left(x^2+9x+19\right)^2\)
NT
24 tháng 8 2021
b. \(x^2+y^2+2x+2y+2\left(x+1\right)\left(y+1\right)+2\)
\(=\left(x^2+2x+1\right)+2\left(x+1\right)\left(y+1\right)+\left(y^2+2y+1\right)\)
\(=\left(x+1\right)^2+2\left(x+1\right)\left(y+1\right)+\left(y+1\right)^2\)
\(=\left(x+1+y+1\right)^2=\left(x+y+2\right)^2\)
c. \(x^2-2x\left(y+2\right)+y^2+4y+4\)
\(=x^2-2x\left(y+2\right)+\left(y+2\right)^2\)
\(=\left(x-y-2\right)^2\)
d. \(x^2+2x\left(y+1\right)+y^2+2y+1\)
\(=x^2+2x\left(y+1\right)+\left(y+1\right)^2\)
\(=\left(x+y+1\right)^2\)
4 tháng 9 2021
\(A=x^2+4x+5=\left(x+2\right)^2+1\ge1\)
Dấu \("="\Leftrightarrow x=-2\)
\(B=x^2+10x-1=\left(x+5\right)^2-26\ge-26\)
Dấu \("="\Leftrightarrow x=-5\)
\(C=5-4x+4x^2=\left(2x-1\right)^2+4\ge4\)
Dấu \("="\Leftrightarrow x=\dfrac{1}{2}\)
\(D=x^2+y^2-2x+6y-3=\left(x-1\right)^2+\left(y+3\right)^2-13\ge-13\)
Dấu \("="\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-3\end{matrix}\right.\)
\(E=2x^2+y^2+2xy+2x+3=\left(x+y\right)^2+\left(x+1\right)^2+2\ge2\)
Dấu \("="\Leftrightarrow x=-y=-1\Leftrightarrow\left\{{}\begin{matrix}x=-1\\y=1\end{matrix}\right.\)
4 tháng 9 2021
\(A=x^2+4x+5\)
\(=x^2+4x+4+1\)
\(=\left(x+2\right)^2+1\ge1\forall x\)
Dấu '=' xảy ra khi x=-2
\(C=4x^2-4x+5\)
\(=4x^2-4x+1+4\)
\(=\left(2x-1\right)^2+4\ge4\forall x\)
Dấu '=' xảy ra khi \(x=\dfrac{1}{2}\)
TH
6
24 tháng 6 2018
......................?
mik ko biết
mong bn thông cảm
nha ................
6 tháng 8 2022
a: \(=x^2-4x+4+y^2+2y+1\)
\(=\left(x-2\right)^2+\left(y+1\right)^2\)
b: \(=x^2+10x+25+x^2-2xy+y^2\)
\(=\left(x+5\right)^2+\left(x-y\right)^2\)
c: \(=a^2+2ab+b^2+4b^2+4b+1\)
\(=\left(a+b\right)^2+\left(2b+1\right)^2\)
d: \(=2\left(x^2+b^2\right)\)
30 tháng 6 2017
a) Ta có: \(x^2+10x+26+y^2+2y=\left(x^2+10x+25\right)+\left(y^2+2y+1\right)\)
\(=\left(x+5\right)^2+\left(y+1\right)^2\)
b) Ta có: \(a^2+5b^2+2ab+4b+1=\left(a^2+2ab+b^2\right)+\left(4b^2+4b+1\right)\)
\(=\left(a+b\right)^2+\left(2b+1\right)^2\)
c) Ta có: \(4x^2+4x+10+6y+y^2=\left(4x^2+4x+1\right)+\left(y^2+6y+9\right)\)
\(=\left(2x+1\right)^2+\left(y+3\right)^2\)
30 tháng 6 2017
a) \(x^2+10x+26+y^2+2y=x^2+2.5.x+5^2+y^2+2.y.1+1^2\) = \(\left(x+5\right)^2+\left(y+1\right)^2\)
b) \(a^2+5b^2+2ab+4b+1=a^2+2ab+b^2+4b^2+4b+1\)
= \(\left(a+b\right)^2+\left(2b+1\right)^2\)
c) \(4x^2+4x+10+6y+y^2=4x^2+4x+1+y^2+6y+9\)
= \(\left(2x+1\right)^2+\left(y+3\right)^2\)
1)
\(=x^2-4x+4+y^2+2y+1\)
\(=\left(x-2\right)^2+\left(y+1\right)^2\)
2)
\(=a^2+2ab+b^2+a^2-2ax+x^2\)
\(=\left(a+b\right)^2+\left(a-x\right)^2\)
3)
\(=x^2-2x+1+y^2+6y+9\)
\(=\left(x-1\right)^2+\left(y+3\right)^2\)
4)
\(=x^2-2xy+y^2+x^2+10x+25\)
\(=\left(x-y\right)^2+\left(x+5\right)^2\)
5)
\(=a^2+2ab+b^2+4b^2+4b+1\)
\(=\left(a+b\right)^2+\left(2b+1\right)^2\)
1/ x2 - 4x + 5 + y2 + 2y
= ( x2 - 4x + 4 ) + ( y2 + 2y + 1 )
= ( x - 2 )2 + ( y + 1 )2
2/ 2a2 + 2ab - 2ax + x2 + b2
= ( a2 + 2ab + b2 ) + ( x2 - 2ax + a2 )
= ( a + b )2 + ( x - a )2
3/ x2 - 2x + y2 + 6y + 10
= ( x2 - 2x + 1 ) + ( y2 + 6y + 9 )
= ( x - 1 )2 + ( y + 3 )2
4/ 2x2 + y2 - 2xy + 10x + 25
= ( x2 - 2xy + y2 ) + ( x2 + 10x + 25 )
= ( x - y )2 + ( x + 5 )2
5/ a2 + 2ab + 5b2 + 4b + 1
= ( a2 + 2ab + b2 ) + ( 4b2 + 4b + 1 )
= ( a + b )2 + ( 2b + 1 )2