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a, (x4-2x3+2x-1):(x2-1) = \(\frac{\left(x^4-1\right)-\left(2x^3-2x\right)}{x^2-1}\)
= \(\frac{\left(x^2-1\right)\left(x^2+1\right)-2x\left(x^2-1\right)}{x^2-1}\) =\(\frac{\left(x^2-1\right)\left(x^2+1-2x\right)}{x^2-1}\)
= \(x^2+1-2x\)= \(\left(x-1\right)^2\)
b, (8x3-6x2-5x+3):((4x+3)
\(x\left(2-3x\right)+\left(3x^2-x^2\right):x\)
\(=2x-3x^2+3x^2-x\)
\(=x\)
\(2x\left(x-3y\right)-\left(8x^3y-12x^2y^2\right):2xy\)
\(=2x^2-6xy-4x^2+6xy\)
\(=-2x^2\)
a) \(x^4-2x^2+1=\left(x^2-1\right)^2=\left(x-1\right)^2\left(x+1\right)^2\)
b) \(x^2-y^2-5x+5y=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x-y\right)\left(x+y-5\right)\)
c) \(2x^3-x^2-8x+4\)
\(=x^2\left(2x-1\right)-4\left(2x-1\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(2x-1\right)\)
d) \(x\left(x-y\right)^2+y\left(x-y\right)^2-xy+x^2\)
\(=\left(x+y\right)\left(x-y\right)^2+x\left(x-y\right)\)
\(=\left(x-y\right)\left(x^2-y^2+x\right)\)
e) \(2x^2-5x+2\)
\(=\left(2x^2-x\right)-\left(4x-2\right)\)
\(=x\left(2x-1\right)-2\left(2x-1\right)\)
\(=\left(x-2\right)\left(2x-1\right)\)
1, a, ( x2 - 1 )*( x2 + 2x)
= x4 + 2x3 - x2 - 2x
b, ( 2x - 1 )*( 3x + 2 )*( 3 - x )
= ( 6x2 + 4x - 3x - 2 )*( 3 - x )
= ( 6x2 + x - 2 )*( 3 - x )
= 18x2 - 6x3 + 3x - x2 - 6 + 2x
= -6x3 - 17x2 + 5x - 6
2, b, B = \(8x^3+48x^2+96x+64\)
= \(\left(2x+4\right)^3\)
Thay x = 8 vào B ta có:
B = \(\left(2\cdot8+4\right)^3\)
= ( 16 + 4 )3
= 203
= 8000
mình chỉ làm đc câu b thôi câu a bạn xem lại đề đi hình như câu a sai đề rồi
Mấy bài dài dài kia tí mình làm cho :)
( x - 1 )3 - x( x - 2 )2 + 1
= x3 - 3x2 + 3x - 1 - x( x2 - 4x + 4 ) + 1
= x3 - 3x2 + 3x - x3 + 4x2 - 4x
= x2 - x = x( x - 1 )
2x( 3x + 2 ) - 3x( 2x + 3 )
= 6x2 + 4x - 6x2 - 9x
= -5x
( x + 2 )3 + ( x - 3 )2 - x2( x + 5 )
= x3 + 6x2 + 12x + 8 + x2 - 6x + 9 - x3 - 5x2
= 2x2 + 6x + 17
( 2x + 3 )( x - 5 ) + 2x( 3 - x ) + x - 10
= 2x2 - 7x - 15 + 6x - 2x2 + x - 10
= -25
( x + 5 )( x2 - 5x + 25 ) - x( x - 4 )2 + 16x
= x3 + 53 - x( x2 - 8x + 16 ) + 16x
= x3 + 125 - x3 + 8x2 - 16x + 16
= 8x2 + 125
( -x - 2 )3 + ( 2x - 4 )( x2 + 2x + 4 ) - x2( x - 6 )
= -x3 - 6x2 - 12x - 8 + 2x3 - 16 - x3 + 6x2
= -12x - 24 = -12( x + 2 )
Tương tự ...
a, \(\left(x-1\right)^3-x\left(x-2\right)^2+1=x^3-3x^2+3x-1-x^3+4x^2-4x+1=x^2-x\)
b, \(2x\left(3x+2\right)-3x\left(2x+3\right)=6x^2+4x-6x^2-9x=-5x\)
c, \(\left(x+2\right)^3+\left(x-3\right)^2-x^2\left(x+5\right)=x^3+6x^2+12x+8+x^2+6x+9-x^3-5x^2=2x^2+18x+17\)
\(\left(2x-3\right)\left(x-2\right)\)
\(=2x^2-4x-3x-6\)
\(=2x^2-7x-6\)
\(\left(x+3\right)^2\)
\(=x^2+2x.3+3^2\)
\(=x^2+6x+9\)
\(A=x^5+2x^4+4x^3+8x^2+16x-2x^4-4x^3-8x^2-16x-32\)
\(=x^5-32\)(1)
Thay x=3 vào (1) ta được:
\(A=3^5-32=243-32=211\)