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\(\left(x-1\right)^2-25\)
\(=x^2-2x+1-25\)
\(=x^2-2x-24\)
\(=x^2-6x+4x-24\)
\(=x.\left(x-6\right)+4.\left(x-6\right)\)
\(=\left(x+4\right).\left(x-6\right)\)
a, \(1-2y+y^2=\left(y+1\right)^2=\left(y+1\right)\left(y+1\right)\)
b, \(\left(x+1\right)^2-25=\left(x+1\right)^2-5^2=\left(x+1-5\right)\left(x+1+5\right)=\left(x-4\right)\left(x+6\right)\)
c, \(1-4x^2=1^2-\left(2x\right)^2=\left(1-2x\right)\left(1+2x\right)\)
d, \(8-27x^3=2^3-\left(3x\right)^3=\left(2-3x\right)\left(4+6x+9x^2\right)\)
\(a.\\ 1-2y+y^2\\ =\left(y-1\right)^2\)
.\(b.\\\left(x+1\right)^2-25\\ =\left(x+1-5\right)\left(x+1+5\right)\\ =\left(x-4\right)\left(x+6\right)\)
\(c.\\ 1-4x^2\\ =\left(1-2x\right)\left(1+2x\right)\)
\(d.\\ 8-27x^3\\ =\left(2\right)^3-\left(3x\right)^3\\ =\left(2-3x\right)\left(4+6x+9x^2\right)\)
\(e.\\ 27+27x+9x^2+x^3\\ =3^3+3.3^2.x+3.3.x^2+x^3\\ =\left(x+3\right)^3\)
\(f.\\ 8x^3-12x^2y+6xy^2-y^3\\ =\left(2x\right)^3-3.\left(2x\right)^2.y+3.2x.y^2-y^3\\ =\left(2x-y\right)^3\)
\(g.\\ x^3+8y^3\\ =x^3+\left(2y\right)^3\\ =\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)
\(10x\left(x-y\right)-6y\left(y-x\right)\)
\(=10x\left(x-y\right)+6x\left(x-y\right)\)
\(=\left(10x+6x\right)\left(x-y\right)\)
\(c,3x^2+5y-3xy-5x\)
\(=\left(3x^2-3xy\right)+\left(5y-5x\right)\)
\(=3x\left(x-y\right)-5\left(x-y\right)\)
\(=\left(3x-5\right)\left(x-y\right)\)
\(e,27+27x+9x^2=3\left(9+9x+x^2\right)\)
\(a.1-2y+y^2\\ =\left(1-y\right)^2\)
\(b.\left(x+1\right)^2-25\\ =\left(x+1\right)^2-5^2\\ =\left[\left(x+1\right)-5\right]\left[\left(x+1\right)+5\right]\\ =\left(x+1-5\right)\left(x+1+5\right)\\ =\left(x-4\right)\left(x+6\right)\)
\(c.1-4x^2\\ =1^2-\left(2x\right)^2\\ =\left(1-2x\right)\left(1+2x\right)\)
\(d.8-27x^3\\ =2^3-\left(3x\right)^3\\ =\left(2-3x\right)\left(4+6x+9x^2\right)\)
\(e.27+27x+9x^2+x^3\\ =3^3+3.3^2.x+3.3.x^2+x^3\\ =\left(3+x\right)^3\)
\(f.8x^3-12x^2y+6xy^2-y^3\\ =\left(2x\right)^3-3.\left(2x\right)^2.y+3.2x.y^2-y^3\\ =\left(2x-y\right)^3\\\)
\(g.x^3+8y^3\\ =x^3+\left(2y\right)^3\\ =\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)
\(h.\left(x^2+1\right)^2-4x^2\\ =\left(x^2+1\right)^2-\left(2x\right)^2\\ =\left[\left(x^2+1\right)-2x\right]\left[\left(x^2+1\right)+2x\right]\\ =\left(x^2+1-2x\right)\left(x^2+1+2x\right)\)
Bài làm:
a, 1-4x2
=1-(2x)2
=(1-2x).(1+2x)
b, 8-27x3
=23-(3x)3
=(2-3x).(4+6x+9x2)
Các câu còn lại bạn dùng hằng đẳng thức là phân tích được ra thôi
1 - 4x^2
= 1^2 - ( 2x )^2
= ( 1 - 2x ) ( 1 + 2x )
8 - 27x^ 3
= 2^3 - ( 3x )^3
= ( 2 - 3x ) [ 2^2 + 2 * 3x + ( 3x )^2 ]
= ( 2 - 3x ) ( 4 + 6x + 9x^2 )
= ( 2 - 3x ) ( 9x^2 + 6x + 4 )
27 + 27x + 9x^2 + x^3
= x^3 + 9x^2 + 27x + 27
= x^3 + 3x^2 + 6x^2 + 18x + 9x + 27
= x^2 ( x + 3 ) + 6x ( x + 3 ) + 9 ( x + 3 )
= ( x + 3 ) ( x^2 + 6x + 9 )
= ( x + 3 ) ( x + 3 )^2
= ( x + 3 )^3
x^2 + 4x - 5
= x^2 - x + 5x - 5
= x ( x - 1 ) + 5 ( x - 1 )
= ( x + 1 ) ( x - 5 )
a. \(1-2y+y^2=\left(1-y\right)^2\)
b. \(\left(x+1\right)^2-25=\left(x+1+5\right)\left(x+1-5\right)=\left(x+6\right)\left(x-4\right)\)
c. \(1-4x^2=\left(1+2x\right)\left(1-2x\right)\)
d. \(8-27x^3=\left(2-3x\right)\left(4+6x+9x^2\right)\)
e. \(27+27x+9x^2+x^3=\left(x+3\right)^3\)
f, \(8x^3-12x^2y+6xy^2-y^3=\left(2x-y\right)^3\)
g, \(x^3+8y^3=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)
\(\left(a\right)1-2y+y^2\)
\(\Leftrightarrow y^2-2y+1\)
\(\Leftrightarrow\left(y-1\right)^2\)
\(\left(b\right)\left(x+1\right)^2-25\)
\(\Leftrightarrow\left(x+1\right)^2-5^2\)
\(\Leftrightarrow\left(x-4\right)\left(x+6\right)\)
\(\left(c\right)1-4x^2\)
\(\Leftrightarrow1-\left(2x\right)^2\)
\(\Leftrightarrow\left(1-2x\right)\left(1+2x\right)\)
\(\left(d\right)8-27x^3\)
\(\Leftrightarrow2^3-\left(3x\right)^3\)
\(\Leftrightarrow\left(2-3x\right)\left(4+6x+9x^2\right)\)
\(\left(e\right)27+27x+9x^2+x^3\)
\(\Leftrightarrow\left(x+3\right)^3\)
\(\left(f\right)8x^3-12x^2y+6xy^2-y^3\)
\(\Leftrightarrow\left(2x\right)^3-12x^2y+6xy^2-y^3\)
\(\Leftrightarrow\left(2x-y\right)^3\)
\(\left(g\right)x^3+8y^3\)
\(\Leftrightarrow\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)
a) 1 - 2y + y2
= (1-y)2
b) ( x + 1 )2 - 25
=( x + 1 )2 - 52
=(x+1+5)(x+1-5)
\(1-2y+y^2=\left(y-1\right)^2\)
\(\left(x+1\right)^2-25=\left(x-1\right)^2-5^2=\left(x-6\right)\left(x+4\right)\)
\(1-4x^2=1-\left(2x\right)^2=\left(1-2x\right)\left(1+2x\right)\)
\(8-27x^3=\left(2-3x\right)\left(4+6x+9x^2\right)\)
\(27+27x+9x^2+x^3=\left(x+3\right)^3\)
\(8x^3-12x^2y+6xy^2-y^3=\left(2x-y\right)^3\)
\(x^3+8y^3=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)
Tham khảo nhé~
Mấy cái này chỉ áp dụng HĐT thoyy nha!
\(a,1-2y+y^2=\left(1-y\right)^2\)
\(b,\left(x-1\right)^2-25=\left(x-1-5\right)\left(x-1+5\right)=\left(x-6\right)\left(x+4\right)\)
\(c,1-4x^2=\left(1-2x\right)\left(1+2x\right)\)
\(d,8-27x^3=\left(2-3x\right)\left(4+6x+9x^2\right)\)
\(e,27+27x+9x^2+x^3=\left(x+3\right)^3\)
\(f,8x^3-12x^2y+9xy^2-y^3=\left(2x-y\right)^2\)
\(g,x^3+8y^3=\left(x+2y\right)\left(x^2-2xy+y^2\right)=\left(x+2y\right)\left(x-y\right)^2\)
=.= hok tốt!!
a: \(=\left(x+1+5\right)\left(x+1-5\right)=\left(x+6\right)\left(x-4\right)\)
b: =(1-2x)(1+2x)
c: \(=\left(2-3x\right)\left(4+6x+9x^2\right)\)
d: =(x+3)^3
e: \(=\left(2x-y\right)^3\)
f: =(x+2y)(x^2-2xy+4y^2)