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a) 85 .12,7 + 5.3.12,7 = 12,7 . ( 85 + 5.3 ) = 12,7 . (85+15) = 12,7 . 100 = 1270
b) 52.143 - 52.39 - 8.26 = 52.143 - 52.39 - 4.2.26 = 52.143 - 52.39 - 4.52 = 52.( 143 -39 - 4 ) = 52 . 100 = 5200
phân tích :
5x - 20y = 5 .(x - 4y)
5x(x-1)-3x.(x-1) = (x-1).(5x-3x) = 2x(x-1) hoặc 5x(x-1)-3x(x-1) = x(x-1)(5-3) = 2x(x-1)
x.(x+y)-5x-5y = x(x+y) - 5 (x+y) = (x+y)(x-5)
a, \(\left(3x-6y\right)x+y\left(x-2y\right)=\left(3x+y\right)\left(x-2y\right)\)
b, \(3\left(x-y\right)-5x\left(y-x\right)=\left(3+5x\right)\left(x-y\right)\)
c, \(\dfrac{2}{5}x\left(y-1\right)+\dfrac{2}{5}y\left(1-y\right)=\left(\dfrac{2}{5}x-\dfrac{2}{5}y\right)\left(y-1\right)=\dfrac{2}{5}\left(x-y\right)\left(y-1\right)\)
d, \(x\left(x-1\right)-y\left(1-x\right)=\left(x+y\right)\left(x-1\right)\)
b ) 5 x ( x - 1 ) - 3x ( x - 1 )
= ( 5x - 3x ) ( x - 1 )
= 2x ( x - 1 )
c ) x ( x + y ) - 5 x - 5y
= x ( x + y ) - 5 ( x + y )
= ( x - 5 ) (x + y )
d ) x ^ 2 + xy + x
= x ( x + y + 1 )
e ) x ( x - y ) + y ( y - x )
= x ( x - y ) - y ( x - y )
= ( x - y ) ( x -y )
= ( x - y ) 2
a, 5x(x-1)-3x(x-1)=(5x-3x)(x-1)=2x(x-1)
b, x(x+y)-5x-5y=x(x+y)-5(x+y)=(x-5)(x+y)
c, x2+xy+x=x(x+y+1)
d, x(x-y)+y(y-x)=x(x-y)-y(x-y)=(x-y)(x-y)=(x-y)2
b)5x(x-1)-3x(x-1)=x(x-1).(5-3)=x(x-1).2
c)x(x+y)-5x-5y=x(x+y)-(5x+5y)=x(x+y)-[5(x+y)[=(x+y).(x-5)
d)x^2+xy+x=x(x+y+1)
e)x(x-y)+y(y-x)=x(x-y)-(x-y).y=(x-y).(x-y)
a) 20x - 5y
= 5(4x - y)
b) 5x(x - 1)- 3x(x - 1)
= 2x(x - 1)
c) x(x + y) - 6x - 6y
= x(x + y) - (6x + 6y)
= x(x + y) - 6(x + y)
= (x + y)(x - 6)
d) 6x³ - 9x²
= 3x²(2x - 3)
e) 4x²y - 8xy² + 10x²y²
= 2xy(2x - 4y + 5xy)
g) 20x²y - 12x³
= 4x²(5y - 3x)
h) 8x⁴ + 12x²y⁴ - 16x³y⁴
= 4x²(2x² + 3y⁴ - 4xy⁴)
k) 4xy² + 8xyz
= 4xy(y + 2z)
\(a,14x^2y-21xy^2+28x^2y^2=7xy\left(x-3y+4xy\right)\\ b,x\left(x+y\right)-5x-5y=x\left(x+y\right)-5\left(x+y\right)=\left(x+y\right)\left(x-5\right)\\ c,10x\left(x-y\right)-8\left(y-x\right)=10x\left(x-y\right)+8\left(x-y\right)=\left(x-y\right)\left(10x+8\right)=2\left(x-y\right)\left(5x+4\right)\)
\(d,\left(3x+1\right)^2-\left(x+1\right)^2=\left(3x+1-x-1\right)\left(3x+1+x+1\right)=2x\left(4x+2\right)=4x\left(2x+1\right)\)\(e,x^3+y^3+z^3-3xyz=\left(x+y+z\right)\left(x^2+y^2+z^2-xy-yz-zx\right)+3xyz-3xyz=\left(x+y+z\right)\left(x^2+y^2+z^2-xy-yz-zx\right)\)
tính nhanh .
a) 85 .12,7 + 5.3.12,7 = 12,7 . ( 85 + 5.3 ) = 12,7 . (85+15) = 12,7 . 100 = 1270
b) 52.143 - 52.39 - 8.26 = 52.143 - 52.39 - 4.2.26 = 52.143 - 52.39 - 4.52 = 52.( 143 -39 - 4 ) = 52 . 100 = 5200
phân tích :
5x - 20y = 5 .(x - 4y)
5x(x-1)-3x.(x-1) = (x-1).(5x-3x) = 2x(x-1) hoặc 5x(x-1)-3x(x-1) = x(x-1)(5-3) = 2x(x-1)
x.(x+y)-5x-5y = x(x+y) - 5 (x+y) = (x+y)(x-5)
85.12,7+5.3 .12,7
= (85+5.3.)12,7
= 100 . 12,7
=1270
52.143-52.39-8.26
=52 . 143 - 52 . 39 - 4 . 2 . 26
= 52 . 143 - 52 . 39 - 52 . 4
= 52 . ( 143 - 39 - 4)
= 52 . 100
= 5200