28 + 5x =4x -30
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x + 2x + 3x + 4x + 5x = x + 28
x + 2x + 3x + 4x + 5x - x = 28
14x = 28
x = 28 : 14
x = 2
x + 2x + 3x + 4x + 5x = x + 28
=> x + 2x + 3x + 4x + 5x - x = 28
=> x x ( 1 + 2 + 3 + 4 + 5 - 1 ) = 28
=> x x 14 = 28
=> x = 28 : 14
=> x = 2
Vậy x = 2
Chúc bạn học tốt !!!
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\(28+5x=4x-30\)
\(\Leftrightarrow5x-4x=-30-28=-58\)
\(\Leftrightarrow x=-58\)
Vậy x = - 58
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a: \(=20x^2-25x-20x^2+24x-30=-x-30\)
b: \(\Leftrightarrow12x-6x^2+6x^2-15x=12\)
=>-3x=12
hay x=-4
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a )
\(5x\left(4x-5\right)-4x\left(5x-6\right)=30\)
\(\Rightarrow20x^2-25x-20x^2+24x=30\)
\(\Rightarrow-x=30\)
\(\Rightarrow x=-30\)
Vậy ...
b )
\(2x\left(6-3x\right)+3x\left(2x-5\right)=12\)
\(\Rightarrow12x-6x^2+6x^2-15x=12\)
\(\Rightarrow-3x=12\)
\(\Rightarrow x=-4\)
Vậy ...
a) \(5x\left(4x-5\right)-4x\left(5x-6\right)-30\)
\(\Rightarrow20x^2-25x-20x^2+24x=30\)
\(\Rightarrow-1x=30\)
\(\Rightarrow x=-30\)
Vậy x = -30
b) \(2x\left(6-3x\right)+3x\left(2x-5\right)=12\)
\(\Rightarrow12x-6x^2+6x^2-15x=12\)
\(\Rightarrow-3x=12\)
\(\Rightarrow x=-4\)
Vậy x = -4
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 3x2 + 12x =0
<=> 3x( x+ 4)=0
<=> \(\orbr{\begin{cases}3x=0\\x+4=0\end{cases}}\) <=>\(\orbr{\begin{cases}x=0\\x=-4\end{cases}}\)
d) \(4x^3=4x\)
<=> \(4x^3-4x=0\)
<=> 4x( x2 -1) =0
<=> 4x ( x - 1) ( x+ 1) =0
<=> 4x=0 hoac x-1=0 hoac x+1=0
<=> x=0 hoac x=1 hoac x=-1
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(-2x).(-4x)+28=100 5x.(-x)^2+1=6 3x^2+12x=0 4x^3=4x
x.(-2-4)=100-28 5x.x^2=6-1 3x(x+4)=0 4x^3-4x=0
-6x=72 5.x^3=5 =>3x=0 hoặc x+4=0 4x(x^2-1)=0
x=-12 x^3=1 (bạn tự giải nốt nhé) =>4x=0 hoặc x^2-1=0
x=1 t.hợp1:x^2-1=0
x^2=1=> ko có gtrị nào của x thỏa mãn
(t.hợp còn lại bạn tự giải nhé)
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\(a,\) \(5x\left(4-x\right)+\left(5x^2-12\right)=x+6\)
\(< =>20x-5x^2+5x^2-12-x-6=0\)
\(< =>19x-18=0\)
\(< =>x=\dfrac{18}{19}\)
\(b,\left(2x-7\right)\left(5+4x\right)-8\left(x^2-4x+5\right)=-30\)
\(< =>10x+8x^2-35-28x-8x^2+24x-40+30=0\)
\(< =>6x-45=0< =>x=\dfrac{45}{6}=7,5\)
a) \(5x\left(4-x\right)+\left(5x^2-12\right)=x+\Rightarrow6\\ \Leftrightarrow20x-5x^2+5x^2-12=x+6\\ \Leftrightarrow20x-12=x+6\\\Rightarrow20x-x=6+12\\ \Rightarrow19x=18\\ \Rightarrow x=\dfrac{18}{19}\)
b) \(\left(2x-7\right)\left(5+4x\right)-8\left(x^2-3x+5\right)=-30\\ \Rightarrow10x+8x^2-35-28x-8x^2+24x-40=-30\\ \Rightarrow6x-75=-30\\ \Rightarrow6x=45\\ \Rightarrow x=\dfrac{15}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
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a) 4(x+2) - 7(2x - 1) + 9(3x - 4)=30
⇔4x+8 - 14x + 7 + 27x - 36 = 30
⇔ 17x = 51
⇔ x = 3
b) 2(5x - 8) - 3(4x - 5) = 4(3x - 4) + 11
⇔ 10x - 16 - 12x + 15 = 12x - 16 + 11
⇔ -14x = -4
⇔ x= \(\frac{2}{7}\)
c) 5x(1 - 2x) - 3x(x + 18) = 0
⇔ 5x - 10x\(^2\) - 3x\(^2\) -54x =0
⇔ -13x\(^2\) -49 x = 0
⇔ -x ( 13x + 49 ) =0
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\13x+49=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\frac{-49}{13}\end{matrix}\right.\)
d) 5x - 3{4x - 2[4x - 3(5x - 2)]} = 182
⇔ 5x - 3[ 4x - 2( 4x - 15x + 6 ) ]= 182
⇔5x - 3 ( 4x - 8x + 30x - 12 ) = 182
⇔ 5x - 3 ( 26x - 12 ) = 182
⇔ 5x - 78x + 36 = 182
⇔ - 73x = 146
⇔ x = -2
28 + 5x =4x -30
5x-4x =-30+28
1x = -58
x =-58:1
x =-58
thanks you very much