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16 tháng 6 2023
`@` `\text {Ans}`
`\downarrow`
`a)`
`3x(4x-1) - 2x(6x-3) = 30`
`=> 12x^2 - 3x - 12x^2 + 6x = 30`
`=> 3x = 30`
`=> x = 30 \div 3`
`=> x=10`
Vậy, `x=10`
`b)`
`2x(3-2x) + 2x(2x-1) = 15`
`=> 6x- 4x^2 + 4x^2 - 2x = 15`
`=> 4x = 15`
`=> x = 15/4`
Vậy, `x=15/4`
`c)`
`(5x-2)(4x-1) + (10x+3)(2x-1) = 1`
`=> 5x(4x-1) - 2(4x-1) + 10x(2x-1) + 3(2x-1)=1`
`=> 20x^2-5x - 8x + 2 + 20x^2 - 10x +6x - 3 =1`
`=> 40x^2 -17x - 1 = 1`
`d)`
`(x+2)(x+2)-(x-3)(x+1)=9`
`=> x^2 + 2x + 2x + 4 - x^2 - x + 3x + 3=9`
`=> 6x + 7 =9`
`=> 6x = 2`
`=> x=2/6 =1/3`
Vậy, `x=1/3`
`e)`
`(4x+1)(6x-3) = 7 + (3x-2)(8x+9)`
`=> 24x^2 - 12x + 6x - 3 = 7 + (3x-2)(8x+9)`
`=> 24x^2 - 12x + 6x - 3 = 7 + 24x^2 +11x - 18`
`=> 24x^2 - 6x - 3 = 24x^2 + 18x -11`
`=> 24x^2 - 6x - 3 - 24x^2 + 18x + 11 = 0`
`=> 12x +8 = 0`
`=> 12x = -8`
`=> x= -8/12 = -2/3`
Vậy, `x=-2/3`
`g)`
`(10x+2)(4x- 1)- (8x -3)(5x+2) =14`
`=> 40x^2 - 10x + 8x - 2 - 40x^2 - 16x + 15x + 6 = 14`
`=> -3x + 4 =14`
`=> -3x = 10`
`=> x= - 10/3`
Vậy, `x=-10/3`
24 tháng 2 2023
a: \(=\dfrac{2x^4+x^3-5x^2-3x-3}{x^2-3}\)
\(=\dfrac{2x^4-6x^2+x^3-3x+x^2-3}{x^2-3}\)
\(=2x^2+x+1\)
b: \(=\dfrac{x^5+x^2+x^3+1}{x^3+1}=x^2+1\)
c: \(=\dfrac{2x^3-x^2-x+6x^2-3x-3+2x+6}{2x^2-x-1}\)
\(=x+3+\dfrac{2x+6}{2x^2-x-1}\)
d: \(=\dfrac{3x^4-8x^3-10x^2+8x-5}{3x^2-2x+1}\)
\(=\dfrac{3x^4-2x^3+x^2-6x^3+4x^2-2x-15x^2+10x-5}{3x^2-2x+1}\)
\(=x^2-2x-5\)
YN
21 tháng 4 2022
`Answer:`
\(f\left(x\right)=5x-3x^2+2x^4-3x-x^4-5\)
\(=\left(2x^4-x^4\right)-3x^2+\left(5x-3x\right)-5\)
\(=x^4-3x^2+2x-5\)
\(g\left(x\right)=-2x^3+10x-1-7x^2+x^4-15x+10x^2\)
\(=x^4-2x^3+\left(-7x^2+10x^2\right)+\left(10x-15x\right)-1\)
\(=x^4-2x^3+3x^2-5x-1\)
\(f\left(x\right)+g\left(x\right)=\left(x^4-3x^2+2x-5\right)+\left(x^4-2x^3+3x^2-5x-1\right)\)
\(=\left(x^4+x^4\right)-2x^3+\left(-3x^2+3x^2\right)+\left(2x-5x\right)+\left(-5-1\right)\)
\(=2x^4-2x^3-3x-6\)
TN
3 tháng 9 2018
\(A=\frac{x^2-10x+36}{x-5}=\frac{x^2-10x+25+9}{x-5}\) \(=\frac{\left(x-5\right)^2+9}{x-5}=x-5+\frac{9}{x-5}\)
để \(A\in Z\)
<=> \(\frac{9}{x-5}\in Z\)mà \(x\in Z\)
=> \(x-5\inƯ\left(9\right)\)
=> \(x-5\in\left(1;-1;3;-3;9;-9\right)\)
=> \(x\in\left(6;4;8;2;14;-4\right)\)
học tốt
14 tháng 6 2020
a) Ta có: \(f\left(x\right)=5x-3x^2+2x^4-3x-x^4-5\)
\(=x^4-3x^2+2x-5\)
Ta có: \(g\left(x\right)=2x^3+10x-1-7x^2-15x+10x^2\)
\(=2x^3+3x^2-5x-1\)
b) Ta có: f(x)+g(x)
\(=x^4-3x^2+2x-5+2x^3+3x^2-5x-1\)
\(=x^4-2x^3-3x-6\)
Ta có: f(x)-g(x)
\(=x^4-3x^2+2x-5-2x^3-3x^2+5x+1\)
\(=x^4-2x^3-6x^2+7x-4\)
KH
22 tháng 9 2018
* Trả lời:
\(\left(1\right)\) \(-3\left(1-2x\right)-4\left(1+3x\right)=-5x+5\)
\(\Leftrightarrow-3+6x-4-12x=-5x+5\)
\(\Leftrightarrow6x-12x+5x=3+4+5\)
\(\Leftrightarrow x=12\)
\(\left(2\right)\) \(3\left(2x-5\right)-6\left(1-4x\right)=-3x+7\)
\(\Leftrightarrow6x-15-6+24x=-3x+7\)
\(\Leftrightarrow6x+24x+3x=15+6+7\)
\(\Leftrightarrow33x=28\)
\(\Leftrightarrow x=\dfrac{28}{33}\)
\(\left(3\right)\) \(\left(1-3x\right)-2\left(3x-6\right)=-4x-5\)
\(\Leftrightarrow1-3x-6x+12=-4x-5\)
\(\Leftrightarrow-3x-6x+4x=-1-12-5\)
\(\Leftrightarrow-5x=-18\)
\(\Leftrightarrow x=\dfrac{18}{5}\)
\(\left(4\right)\) \(x\left(4x-3\right)-2x\left(2x-1\right)=5x-7\)
\(\Leftrightarrow4x^2-3x-4x^2+2x=5x-7\)
\(\Leftrightarrow-x-5x=-7\)
\(\Leftrightarrow-6x=-7\)
\(\Leftrightarrow x=\dfrac{7}{6}\)
\(\left(5\right)\) \(3x\left(2x-1\right)-6x\left(x+2\right)=-3x+4\)
\(\Leftrightarrow6x^2-3x-6x^2-12x=-3x+4\)
\(\Leftrightarrow-15x+3x=4\)
\(\Leftrightarrow-12x=4\)
\(\Leftrightarrow x=-\dfrac{1}{3}\)
TT
0
TT
1
Ta có : |3x + 2| \(\ge\)0 \(\forall\)x
|2x + 3| \(\ge\)0 \(\forall\)x
|x + 1| \(\ge\)0 \(\forall\)x
=> |3x + 2| + |2x + 3| + |x + 1| \(\ge\)0 \(\forall\)x => 10x \(\ge\)0 => x \(\ge\)0
Với : x \(\ge\)0 => 3x + 2 + 2x + 3 + x + 1 = 10x
=> 6x + 6 = 10x
=> 6 = 10x - 6x
=> 4x = 6
=> x = 3/2