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Ta có : (2x + 5)2 - (x - 9)2
= (2x + 5 - x + 9)(2x + 5 + x - 9)
= (x + 14)(3x - 4)
a) \(x^5+x-1\)
\(=x^5+x^4+x^3+x^2-x^4-x^3-x^2+x-1\)
\(=\left(x^5-x^4+x^3\right)+\left(x^4-x^3+x^2\right)-\left(x^2-x+1\right)\)
\(=x^3\left(x^2-x+1\right)+x^2\left(x^2-x+1\right)-\left(x^2-x+1\right)\)
\(=\left(x^2-x+1\right)\left(x^3+x^2-1\right)\)(còn 1 cách nữa là thêm bớt \(x^2\)vào bạn nhé!)
b) \(x^7+x^2+1\)
\(=x^7-x+x^2+x+1\)
\(=x\left(x^6-1\right)+\left(x^2+x+1\right)\)
\(=x\left(x^3+1\right)\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x\left(x^3+1\right)\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x^3+1\right)\left(x-1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left(x^5-x^4+x^2-x+1\right)\)
(Chúc bạn học tốt và nhớ tíck cho mình với nhé!)
A= \(x.\left\{\left[x.\left(x^2-7\right)\right]^2-6^2\right\}=x.\left[x.\left(x^2-7\right)-6\right].\left[x.\left(x^2-7\right)+6\right]\)
A=\(x.\left[x^3-7x-6\right].\left[x^3-7x+6\right]\)
A= \(x.\left(x-3\right).\left(x+1\right).\left(x+2\right).\left(x+3\right).\left(x-1\right).\left(x-2\right)\)
x^7+x^2+2
=(x^7+x^6+x^5)-(x^6+x^5+x^4)+(x^4+x^3+x^2) +(1 -x^3)
=x^5(x^2+1)-x^4(x^2+1)+x^2(x^2+1)+(1-x)(1+x+x^2)
=(x^2+1)(x^5-x^4+x^2-x+1)
x7+x6+x5-x6-x5-x4+x5+x4+x3-x3-x2-x1+x2+x1+1
= x5(x2+x+1) - x4(x2+x+1)+x3(x2+x+1)-x(x2+x+1) +(x2+x+1)
=(x2+x+1)( x5-x4+x3-x+1)
────(♥)(♥)(♥)────(♥)(♥)(♥) __ ɪƒ ƴσυ’ʀє αʟσηє,
──(♥)██████(♥)(♥)██████(♥) ɪ’ʟʟ ɓє ƴσυʀ ѕɧα∂σѡ.
─(♥)████████(♥)████████(♥) ɪƒ ƴσυ ѡαηт тσ cʀƴ,
─(♥)██████████████████(♥) ɪ’ʟʟ ɓє ƴσυʀ ѕɧσυʟ∂єʀ.
──(♥)████████████████(♥) ɪƒ ƴσυ ѡαηт α ɧυɢ,
────(♥)████████████(♥) __ ɪ’ʟʟ ɓє ƴσυʀ ρɪʟʟσѡ.
──────(♥)████████(♥) ɪƒ ƴσυ ηєє∂ тσ ɓє ɧαρρƴ,
────────(♥)████(♥) __ ɪ’ʟʟ ɓє ƴσυʀ ѕɱɪʟє.
─────────(♥)██(♥) ɓυт αηƴтɪɱє ƴσυ ηєє∂ α ƒʀɪєη∂,
───────────(♥) __ ɪ’ʟʟ ʝυѕт ɓє ɱє.
1, a ( a - b ) ( a + b ) - ( a + b ) ( a2 - ab + b2 )
= ( a + b ) [ a ( a - b ) - ( a2 - ab + b2 )
= ( a + b ) ( a2 - ab - a2 + ab - b2 )
= ( a + b ) b2
.......
2, 3x ( x + 7 )2 - 11x2 ( x + 7 ) + 9 ( x + 7 )
= ( x + 7 ) [( 3x ( x + 7 ) - 11x2 + 9 ]
= ( x + 7 ) ( 3x3 + 21x - 11x2 + 9)
= ( x + 7 ) ( - 8x2 + 21x + 9 )
..........
3, 4x ( x - 2y ) + 8y ( 2y - x )
= 4x ( x - 2y ) - 8y ( x - 2y )
= ( 4x - 8y ) ( x - 2y )
= 4 ( x - 2y ) ( x - 2y )
= 4 ( x - 2y )2
a, x^2 - x - y^2 - y
= (x^2 - y^2) - ( x+ y)
= ( x- y)(x+y) - ( x+y )
= ( x - y - 1 )(x+ y)
b, x^2+ 6x + 9 - y^2
= ( x+ 3)^2 - y^2
= ( x+ 3 -y)( x + 3 +y)
\(9\left(x-5\right)^2-\left(x+7\right)^2\)
\(=\)\(3^2\left(x-5\right)^2-\left(x+7\right)^2\)
\(=\)\(\left[3\left(x-5\right)\right]^2-\left(x+7\right)^2\)
\(=\)\(\left(3x-15\right)^2-\left(x+7\right)^2\)
\(=\)\(\left(3x-15-x-7\right)\left(3x-15+x+7\right)\)
\(=\)\(\left(2x-22\right)\left(4x-8\right)\)
\(=\)\(2\left(x-11\right).4\left(x-2\right)\)
\(=\)\(8\left(x-11\right)\left(x-2\right)\)
Chúc bạn học tốt ~