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14 tháng 10 2020
1) 4x2 + 5x - 6 = 4x2 + 8x - 3x - 6 = 4x( x + 2 ) - 3( x + 2 ) = ( x + 2 )( 4x - 3 )
2) 5x2 - 18x - 8 = 5x2 - 20x + 2x - 8 = 5x( x - 4 ) + 2( x - 4 ) = ( x - 4 )( 5x + 2 )
3) 2x2 + 3x - 27 = 2x2 - 6x + 9x - 27 = 2x( x - 3 ) + 9( x - 3 ) = ( x - 3 )( 2x + 9 ) < đã sửa ._. >
4) 7x2 + 3xy - 10y2 = 7x2 - 7xy + 10xy - 10y2 = 7x( x - y ) + 10y( x - y ) = ( x - y )( 7x + 10y )
5) x2 + 5x - 2 < sai đề ._. >
6) x8 + x7 + 1 = x8 + x7 + x6 - x6 + 1
= ( x8 + x7 + x6 ) - ( x6 - 1 )
= x6( x2 + x + 1 ) - ( x3 - 1 )( x3 + 1 )
= x6( x2 + x + 1 ) - ( x - 1 )( x2 + x + 1 )( x3 + 1 )
= ( x2 + x + 1 )[ x6 - ( x - 1 )( x3 + 1 ) ]
= ( x2 + x + 1 )( x6 - x4 + x3 - x + 1 )
YN
3 tháng 7 2021
\(1.\)
\(4x^2-4x-3\)
\(=4x^2-2x+6x-3\)
\(=2x\left(2x-1\right)+3\left(2x-1\right)\)
\(=\left(2x+3\right)\left(2x-1\right)\)
\(2.\)
\(2x^2-5x-3\)
\(=2x^2-6x+x-3\)
\(=2x\left(x-3\right)+\left(x-3\right)\)
\(=\left(2x+1\right)\left(x-3\right)\)
\(3.\)
\(3x^2-5x-2\)
\(=3x^2+x-6x-2\)
\(=x\left(3x+1\right)-2\left(3x+1\right)\)
\(=\left(3x+1\right)\left(x-2\right)\)
\(4.\)
\(2x^2+5x+2\)
\(=2x^2+4x+x+2\)
\(=2x\left(x+2\right)+\left(x+2\right)\)
\(=\left(2x+1\right)\left(x+2\right)\)
YN
3 tháng 7 2021
\(5.\)
\(6x^2-x-1\)
\(=6x^2-3x+2x-1\)
\(=2x\left(3x+1\right)-\left(3x+1\right)\)
\(=\left(2x-1\right)\left(3x+1\right)\)
\(6.\)
\(6x^2-6x-3\)
\(=3\left(2x^2-2x-1\right)\)
\(7.\)
\(15x^2-2x-1\)
\(=15x^2+3x-5x-1\)
\(=3x\left(5x+1\right)-1\left(5x+1\right)\)
\(=\left(5x+1\right)\left(3x-1\right)\)
\(8.\)
\(x^4-13x^2+36\)
\(=\left(x-3\right)\left(x^3+3x^2-4x-12\right)\)
\(=\left(x-3\right)\left(x-2\right)\left(x^2+5x+6\right)\)
\(=\left(x-3\right)\left(x-2\right)\left(x+2\right)\left(x+3\right)\)
26 tháng 2 2020
\(1) 2x+1=15-5x \)
\(⇔2x+5x=15-1\)
\(⇔7x=14\)
\(⇔x=2\)
vậy pt có 1 nghiệm là x=2
\(2) 3x-2=2x+5\)
\(⇔3x-2x=5+2\)
\(⇔x=7\)
vậy pt có 1 nghiệm là x=7
\(3) 7(x-2)=5(3x+1)\)
\(⇔7x-14=15x+5\)
\(⇔7x-15x=5+14\)
\(⇔-8x=19\)
\(⇔x=-\dfrac{19}{8}\)
vậy pt có 1 nghiệm là x=-\(\dfrac{19}{8}\)
\(4) 2x+5=20-3x\)
\(⇔2x+3x=20-5\)
\(⇔5x=15\)
\(⇔x=3\)
vậy pt có 1 nghiệm là x=3
\(5) -4x+8=0\)
\(⇔-4x=-8\)
\(⇔x=2\)
vậy pt có 1 nghiệm là x=2
\(6) x-3=10-5x\)
\(⇔x+5x=10+3\)
\(⇔6x=13\)
\(⇔x=\dfrac{13}{6}\)
vậy pt có 1 nghiệm là \(x=\dfrac{13}{6}\)
\(7) 3x-1=x+3\)
\(⇔3x-x=3+1\)
\(⇔2x=4\)
\(⇔x=2\)
vậy pt có 1 nghiệm là x=2
\(8) 2(x+1)=5x-7\)
\(⇔2x+2=5x-7\)
\(⇔2x-5x=-7-2\)
\(⇔-3x=-9\)
\(⇔x=3\)
vậy pt có 1 nghiệm là x=3.
12 tháng 6 2018
+) (5x-1). (2x+3)-3. (3x-1)=0
10x^2+15x-2x-3 - 9x+3=0
10x^2 +8x=0
2x(5x+4)=0
=> x=0 hoặc x= -4/5
+) x^3 (2x-3)-x^2 (4x^2-6x+2)=0
2x^4 -3x^3 -4x^4 + 6x^3 - 2x^2=0
-2x^4 + 3x^3-2x^2=0
x^2(-2x^2+x-2)=0
-2x^2(x-1)^2=0
=> x=0 hoặc x=1
+) x (x-1)-x^2+2x=5
x^2 -x -x^2+2x=5
x=5
+) 8 (x-2)-2 (3x-4)=25
8x - 16-6x+8=25
2x=33
x=33/2
16 tháng 8 2017
1) \(5x-5y+x\left(x-y\right)\)
\(=5\left(x-y\right)+x\left(x-y\right)\)
\(=\left(x-y\right)\left(x+5\right)\)
2) \(x^2+4x+3\)
\(=\left(x^2+x\right)+\left(3x+3\right)\)
\(=x\left(x+1\right)+3\left(x+1\right)\)
\(=\left(x+1\right)\left(x+3\right)\)
3) \(x^2-2xy+y^2-z^2\)
\(=\left(x-y\right)^2-z^2\)
\(=\left(x-y-z\right)\left(x-y+z\right)\)
4) \(x\left(x-5\right)-3x+15\)
\(=x\left(x-5\right)-3\left(x-5\right)\)
\(=\left(x-5\right)\left(x-3\right)\)
5) \(y^2-x^2+2x-1\)
\(=y^2-\left(x^2-2x+1\right)\)
\(=y^2-\left(x-1\right)^2\)
\(=\left(x+y-1\right)\left(y-x+1\right)\)
16 tháng 8 2017
\(1.\left(x-y\right)\left(x+5\right)\)
\(2.\left(x+1\right)\left(x+3\right)\)
\(3.\left(x-y-z\right)\left(x-y+z\right)\)
\(4.\left(x-3\right)\left(x-5\right)\)
\(5.\left(y-x+1\right)\left(y+x+1\right)\)
\(7.\left(x+1\right)\left(x-2\right)^2\)
\(8.\left(x-5\right)\left(x+3\right)\)
\(10.\left(y+1\right)\left(2x+z\right)\)
19 tháng 8 2017
1)
5x - 5y + x ( x - y ) = (x-y)(5+x)
2)
x2+4x+3=x2+x+3x+3=(x+1)(x+3)
3)x2-2xy+y2-z2=\(\left(x-y\right)^2-z^2=\left(x-y-z\right)\left(x-y+z\right)\)
19 tháng 8 2017
4)\(x\left(x-5\right)-3x+15=\left(x-3\right)\left(x-5\right)\)
28 tháng 1 2021
a, \(4\left(18-5x\right)-12\left(3x-7\right)=15\left(2x-16\right)-6\left(x+14\right)\)
\(\Leftrightarrow72-20x-36x+84=30x-240-6x-84\)
\(\Leftrightarrow156-56x=24x-324\)
\(\Leftrightarrow-80x+480=0\Leftrightarrow x=-6\)
b, \(5\left(3x+5\right)-4\left(2x-3\right)=5x+3\left(2x-12\right)+1\)
\(\Leftrightarrow15x+25-8x+12=5x+6x-36+1\)
\(\Leftrightarrow7x+37=11x-35\)
\(\Leftrightarrow-4x+72=0\Leftrightarrow x=18\)
28 tháng 1 2021
c, \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)
\(\Leftrightarrow10x-16-12x+15=12x-16+11\)
\(\Leftrightarrow-2x-1=12x-5\)
\(\Leftrightarrow-14x+4=0\Leftrightarrow x=\frac{2}{7}\)
d, \(5x-3\left\{4x-2\left[4x-3\left(5x-2\right)\right]\right\}=182\)
\(\Leftrightarrow5x-3\left[4x-15x+6\right]=182\)
\(\Leftrightarrow5x-3\left(-11x+6\right)=182\)
\(\Leftrightarrow5x+33x-18-182=0\)
\(\Leftrightarrow38x-200=0\Leftrightarrow x=\frac{100}{19}\)
DH
4 tháng 7 2017
a, \(4\left(18-5x\right)-12\left(3x-7\right)=15\left(2x-16\right)-6\left(x+14\right)\)
\(\Rightarrow72-20x-36x+84=30x-240-6x-84\)
\(\Rightarrow-20x-36x-30x+6x=-240-84-72-84\)
\(\Rightarrow-80x=-480\Rightarrow x=6\)
b, \(5\left(3x+5\right)-4\left(2x-3\right)=5x+3\left(2x+12\right)+1\)
\(\Rightarrow15x+25-8x+12=5x+6x+36+1\)
\(\Rightarrow15x-8x-5x-6x=36+1-25-12\)
\(\Rightarrow-4x=0\Rightarrow x=0\)
c, \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)
\(\Rightarrow10x-16-12x+15=12x-16+11\)
\(\Rightarrow10x-12x-12x=-16+11+16-15\)
\(\Rightarrow-14x=-4\Rightarrow x=\dfrac{2}{7}\)
d, \(5x-3\left\{4x-2\left[4x-3\left(5x-2\right)\right]\right\}=182\)
\(\Rightarrow5x-3\left[4x-2\left(4x-15x+6\right)\right]=182\)
\(\Rightarrow5x-3\left(4x-8x+30x-12\right)=182\)
\(\Rightarrow5x-12x+24x-90x+36=182\)
\(\Rightarrow-73x=182-36\)
\(\Rightarrow-73x=146\Rightarrow x=-2\)
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