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bài 1:
a) x2 + 10x + 26 + y2 + 2y
= (x2 + 10x + 25) + (y2 + 2y + 1)
= (x + 5)2 + (y + 1)2
b) z2 - 6z + 5 - t2 - 4t
= (z - 3)2 - (t + 2)2
c) x2 - 2xy + 2y2 + 2y + 1
= (x2 - 2xy + y2) + (y2 + 2y + 1)
= (x - y)2 + (y + 1)2
d) 4x2 - 12x - y2 + 2y + 1
= (4x2 - 12x ) - (y2 + 2y + 1)
= ......................................
ok mk nhé!! 4545454654654765765767587876968345232513546546575675767867876876877687975675
\(x^2+6x+9=\left(x+3\right)^2\)
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\(x^2-x+\dfrac{1}{4}=\left(x-\dfrac{1}{2}\right)^2\)
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\(x^3+12x^2+48x+64=\left(x+4\right)^3\)
1) \(\dfrac{\left(x+5\right)^2+\left(x-5\right)^2}{x^2+25}\)
\(=\dfrac{x^2+10x+25+x^2-10x+25}{x^2+25}\)
\(=\dfrac{2x^2+50}{x^2+25}\)
\(=\dfrac{2\left(x^2+25\right)}{x^2+25}=2\)
2) \(\left(x+3\right)\left(x^2-3x+9\right)-\left(54+x^3\right)\)
\(=x^3+3^3-54-x^3\)
\(=27-54=-27\)
3) \(\left(2x+y\right)^2-\left(y+3x\right)^2\)
\(=4x^2+4xy+y^2-y^2-6xy-9x^2\)
\(=-5x^2-2xy\)
4) \(\left(2x+1\right)^3-\left(2x-1\right)^3-24x^2\)
\(=8x^3+12x^2+6x+1-8x^3+12x^2-6x+1-24x^2\)
\(=2\)
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
a) \(9x^2+6x+1=\left(3x\right)^2+2.3x.1+1^2=\left(3x+1\right)^2\)
b) \(x^2-x+\dfrac{1}{4}=x^2-2.\dfrac{1}{2}x+\left(\dfrac{1}{2}\right)^2=\left(x-0,5\right)^2\)
c) \(x^2y^4-2xy^2+1=\left(xy^2\right)^2-2.xy^2.1+1^2=\left(xy^2-1\right)^2\)
d) \(x^2+\dfrac{2}{3}x+\dfrac{1}{9}=x^2+2.x.\dfrac{1}{3}+\left(\dfrac{1}{3}\right)^2=\left(x+\dfrac{1}{3}\right)^2\)
a) \(9x^2+6x+1\)
\(=\left(3x\right)^2+2.3x.1+1^2\)
\(=\left(3x+1\right)^2\)
\(a,9a^2-6ab=1\) ( kiểm tra lại đề giúp mk)
\(b,25-10x+x^2\)
\(=5^2-2.5.x+x^2\)
\(=\left(5-x\right)^2=\left(x-5\right)^2\)
c, cx kiểm tra và viết rõ đề hộ mk ak
\(d,\left(x-y\right)^2-4\left(x-y\right)+4\)
\(=\left(x-y\right)^2-2.\left(x-y\right).2+2^2\)
\(=\left(x-y-2\right)^2\)
c/ \(x^2-2.x.\frac{1}{x}+\frac{1}{x^2}=\left(x-\frac{1}{x}\right)^2\)
a) \(9x^2+6x+1=\left(3x+1\right)^2\)
b)\(x^2-x+\frac{1}{4}=\left(x-\frac{1}{2}\right)^2\)
c)\(x^2y^4-2xy^2+1=\left(xy^2-1\right)^2\)
d) \(x^2+\frac{2}{3}x+\frac{1}{9}=\left(x+\frac{1}{3}\right)^2\)
a) 9x2 + 6x + 1 = ( 3x + 1 )2
b) x2 - x + 1/4 = ( x - 1/2)2
c) x2 . y4 - 2xy2 + 1 = ( xy2 - 1 ) 2
d) x2 + 2/3x + 1/9 = (x+1/3)2
Ta có 25 x 2 – 20 x y + 4 y 2 = ( 5 x ) 2 – 2 . 5 x . 2 y + ( 2 y ) 2 = ( 5 x – 2 y ) 2
Đáp án cần chọn là: A