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Cả 4 đáp án đều sai, 4 pt đã cho ko có pt nào có nghiệm \(x=-1\)
a: 3x-5>15-x
=>4x>20
hay x>5
b: \(3\left(x-2\right)\left(x+2\right)< 3x^2+x\)
=>3x2+x>3x2-12
=>x>-12
a: 3x-5>15-x
=>3x+x>15+5
=>4x>20
=>x>5
b: \(3\left(x-2\right)\left(x+2\right)<3x^2+x\)
=>\(3\left(x^2-4\right)<3x^2+x\)
=>\(3x^2-12-3x^2-x<0\)
=>-x-12<0
=>x+12>0
=>x>-12
c: \(\left(2x+1\right)^2+3x\left(1-x\right)\le\left(x+2\right)^2\)
=>\(4x^2+4x+1+3x-3x^2\le x^2+4x+4\)
=>\(x^2+7x+1\le x^2+4x+4\)
=>7x+1<=4x+4
=>7x-4x<=4-1
=>3x<=3
=>x<=1
d: \(\frac{5x-20}{3}-\frac{2x^2+x}{2}>\frac{x\left(1-3x\right)}{3}-\frac{5x}{4}\)
=>\(\frac{4\left(5x-20\right)-6\left(2x^2+x\right)}{12}>\frac{4x\left(1-3x\right)-15x}{12}\)
=>\(4\left(5x-20\right)-6\left(2x^2+x\right)>4x\left(1-3x\right)-15x\)
=>\(20x-80-12x^2-6x>4x-12x^2-15x\)
=>14x-80>-11x
=>25x>80
=>\(x>\frac{80}{25}=\frac{16}{5}\)
e: 4-2x<=3x-6
=>-2x-3x<=-6-4
=>-5x<=-10
=>x>=2
f: \(\left(x+4\right)\left(5x-1\right)>5x^2+16x+2\)
=>\(5x^2-x+20x-4>5x^2+16x+2\)
=>19x-4>16x+2
=>3x>6
=>x>2
g: \(x\left(2x-1\right)-8<5-2x\left(1-x\right)\)
=>\(2x^2-x-8<5-2x+2x^2\)
=>-x-8<-2x+5
=>-x+2x<5+8
=>x<13
h: \(\frac{3x-1}{4}-\frac{3\left(x-2\right)}{8}-1>\frac{5-3x}{2}\)
=>\(\frac{2\left(3x-1\right)}{8}-\frac{3\left(x-2\right)}{8}-\frac88>\frac{4\left(5-3x\right)}{8}\)
=>2(3x-1)-3(x-2)-8>4(5-3x)
=>6x-2-3x+6-8>20-12x
=>3x-4>20-12x
=>15x>24
=>\(x>\frac{24}{15}\)
=>x>1,6
a) x2 - 5x - 6 = 0
=> x2 - 2x - 3x - 6 = 0
=> (x2 - 2x) + (-3x - 6) = 0
=> x(x - 2) - 3 (x - 2) = 0
=> (x - 2) (x - 3) = 0
=> x - 2 = 0 => x = 2
x - 3 = 0 => x = 3
còn lại tương tự nhé!! 46566578768698945635655675656788787868789789879789098089364556546
c: =>2x+4>=2x+2-3
=>4>=-1(luôn đúng)
a: 5x+10>3x+3
=>2x>-7
=>x>-7/2
A
A