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a) x2 + 2x +1
= (x + 1)2
b) 9x2 + y2 + 6xy
= (3x + y)2
c) 25a2 + 4b2 - 20ab
= (5a - 2b)2
d) x2 - x + 1/4
= (x - 1/2)2
a, \(25x^2+5xy+\frac{1}{4}y^2=\left(5x\right)^2+2.5x.\frac{1}{2}y+\left(\frac{1}{2}y\right)^2\)
\(=\left(5x+\frac{1}{2}y\right)^2\)
b, \(9x^2+12x+4=\left(3x\right)^2+2.3x.2+2^2=\left(3x+2\right)^2\)
c, \(x^2-6x+5-y^2-4y=\left(x^2-6x+9\right)-\left(y^2+4y+4\right)\)
\(=\left(x-3\right)^2-\left(y+2\right)^2=\left(x-y-5\right)\left(x+y-1\right)\)
d, \(\left(2x-y\right)^2+4\left(x+y\right)^2-4\left(2x-y\right)\left(x+y\right)\)
\(=\left(2x-y\right)^2-2\left(2x-y\right)\left(2x+2y\right)+\left(2x+2y\right)^2\)
\(=\left(2x-y+2x+2y\right)^2=\left(4x+y\right)^2\)
a) (a - 2b)2 = a2 - 2.a.2b + 4b2
= a2 - 4ab + 4b2
b) m2 - 4n2 = m2 - (2n)2 = (m - 2n)(m + 2n)
. Bài 1:
a; 9m^2 + n^2 - 6mn
= (3m)^2 - 2.3m.n + (n)^2
= ( 3m-n )^2
b; x^2-x+1/4
= x^2-2.(x).1/2+(1/2)^2
= (x-1/2)^2
a) \(x^2+2x+1\)
\(=\left(x+1\right)^2\)
b) \(x^2-6x+9\)
\(=\left(x-3\right)^2\)
c) \(x^2+4x+4\)
\(=\left(x+2\right)^2\)
d) \(x^3+9x^2+27x+27\)
\(=\left(x+3\right)^3\)
a) =(3x+y)2
câu b) sao kì quá mik k hiểu bạn xem lại đề đi có viết thiếu dấu k
Bài 1:
a) \(x^2\left(5x^3-x-6\right)\)
\(=x^2.5x^3-x^2.x-x^2.6\)
\(=5x^5-x^3-6x^2\)
b) \(\left(x^2-2xy+y^2\right)\left(x-y\right)\)
\(=x^2\left(x-y\right)-2xy\left(x-y\right)+y^2\left(x-y\right)\)
\(=x^3-x^2y-2x^2y+2xy^2+y^2x-y^3\)
\(=x^3-3x^2y+3xy^2-y^3\)
Bài 2:
a) \(y^2+2y+1\)
\(=\left(y+1\right)^2\)
b) \(9x^2+y^2-6xy\)
\(=\left(3x\right)^2-2.3x.y+y^2\)
\(=\left(3x-y\right)^2\)
c) \(25a^2+4b^2+20ab\)
\(=\left(5a\right)^2+2.5a.2b+\left(2b\right)^2\)
\(=\left(5a+2b\right)^2\)
d) \(x^2-x+\dfrac{1}{4}\)
\(=x^2-2.x.\dfrac{1}{2}+\left(\dfrac{1}{2}\right)^2\)
\(=\left(x-\dfrac{1}{2}\right)^2\)
d) x^2 - x + 1/4
= x^2 - 2.x + 1/4 + (1/2)^2
= ( x - 1/2)^2
1) (x + 1)2
2) (3x + y)2
3) (x - 1/2)2