(2x-1)+1/4=75%
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đơn giản thôi bạn
3 (x + 25)
= 3x + 3*25 (bạn nhân 3 với từng số trong ngoặc) (*là nhân nhé)
= 3x + 75
![](https://rs.olm.vn/images/avt/0.png?1311)
(2\(x-\dfrac{4}{3}\)): \(\dfrac{4}{15}\) - 75% = 9\(\dfrac{1}{4}\)
(2\(x\) - \(\dfrac{4}{3}\)) : \(\dfrac{4}{15}\) - 0,75 = 9,25
(2\(x\) - \(\dfrac{4}{3}\)): \(\dfrac{4}{15}\) = 9,25 + 0,75
(2\(x\) - \(\dfrac{4}{3}\)): \(\dfrac{4}{15}\) = 10
2\(x\) - \(\dfrac{4}{3}\) = 10 \(\times\) \(\dfrac{4}{15}\)
2\(x\) - \(\dfrac{4}{3}\) = \(\dfrac{8}{3}\)
2\(x\) = \(\dfrac{8}{3}\) + \(\dfrac{4}{3}\)
2\(x\) = \(\dfrac{12}{3}\)
2\(x\) = 4
\(x\) = 4:2
\(x\) = 2
\(\left(2x-\dfrac{4}{3}\right)\div\dfrac{4}{15}-75\%=9\dfrac{1}{4}\)
\(\left(2x-\dfrac{4}{3}\right)\div\dfrac{4}{15}-\dfrac{3}{4}=\dfrac{37}{4}\)
\(\left(2x-\dfrac{4}{3}\right)\div\dfrac{4}{15}=10\)
\(2x-\dfrac{4}{3}=\dfrac{8}{3}\)
\(2x=\dfrac{8}{3}+\dfrac{4}{3}\)
\(2x=4\)
\(x=2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
b) 5( 2x + 3 )( x + 2 ) - 2( 5x - 4 )( x - 1 ) = 75
<=> 5( 2x2 + 7x + 6 ) - 2( 5x2 - 9x + 4 ) = 75
<=> 10x2 + 35x + 30 - 10x2 + 18x - 8 = 75
<=> 53x + 22 = 75
<=> 53x = 53
<=> x = 1
c) 2x2 + 3( x - 1 )( x + 1 ) = 5x( x + 1 )
<=> 2x2 + 3( x2 - 1 ) = 5x2 + 5x
<=> 2x2 + 3x2 - 3 - 5x2 - 5x = 0
<=> -3 - 5x = 0
<=> -5x = 3
<=> x = -3/5
![](https://rs.olm.vn/images/avt/0.png?1311)
tao là N nè kqua phần a ra 20/3, phần b là 2.5 còn phần c tao làm rồi nhưng không chắc
![](https://rs.olm.vn/images/avt/0.png?1311)
ai k mình k lại [ chỉ 3 người đầu tiên mà trên 10 điểm hỏi đáp ]
a) 5( 2y + 3 )( y + 2 ) - 2( 5y - 4 )( y - 1 ) = 75
<=> 5( 2y2 + 7y + 6 ) - 2( 5y2 - 9y + 4 ) = 75
<=> 10y2 + 35y + 30 - 10y2 + 18y - 8 = 75
<=> 53y + 22 = 75
<=> 53y = 53
<=> y = 1
b) ( 2x + 3 )2 + ( 2 - 2x )2 + ( 4x + 6 )( 2 - 2x ) = x + 1
<=> 4x2 + 12x + 9 + 4x2 - 8x + 4 - 8x2 - 4x + 12 = x + 1
<=> 25 = x + 1
<=> x = 24
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 7\(x\) - \(x\) = 521 : 519 + 3.22.7
6\(x\) = 53 + 3.4.7
6\(x\) = 125 + 12.7
6\(x\) = 125 + 84
6\(x\) = 209
\(x\) = 209 : 6
\(x\) = \(\dfrac{209}{6}\)
b; 11\(x\) - 7\(x\) + 34 : 33 = 54 + 2\(x\)
4\(x\) + 3 = 625 + 2\(x\)
4\(x\) - 2\(x\) = 625 - 3
2\(x\) = 622
\(x\) = 622 : 2
\(x\) = 311
c; 75 - 5.(\(x-3\))3 = 700
5.(\(x\) - 3)3 = 700 - 75
5.(\(x\) - 3)3 = - 625
(\(x\) - 30)3 = - 625 : 5
(\(x\) - 30)3 = - 125
(\(x-3\))3 = (-5)3
\(x\) - 3 = - 5
\(x\) = - 5 + 3
\(x\) = -2
d, 3.(2\(x\) - 1)2 = 75
(2\(x\) - 1)2 = 75 : 3
(2\(x\) - 1)2 = 25
\(\left[{}\begin{matrix}2x-1=-5\\2x-1=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-5+1\\2x=5+1\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-4\\2x=6\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 3(1-4x) (x-1) +4(3x-2) (x+3)=-27
b) 5(2x+3) (x+2)-2(5x-4) (x-1)=75
![](https://rs.olm.vn/images/avt/0.png?1311)
a. 42 . 46 + 42 . 52
= 42 . (46+52)
= 16 . 98
= 1568
b. -75+58+(-25)
= [-75+(-25)]+58
= -100+58
= -42
c. -4 . 5 . (-25)
= [-4 . (-25)] . 5
= 100 . 5
= 500
\(\left(2x-1\right)+\dfrac{1}{4}=75\%\)
\(\left(2x-1\right)+\dfrac{1}{4}=\dfrac{3}{4}\)
\(2x-1=\dfrac{3}{4}-\dfrac{1}{4}\)
\(2x-1=\dfrac{2}{4}\)
\(2x-1=\dfrac{1}{2}\)
\(2x=\dfrac{1}{2}+1\)
\(2x=\dfrac{1}{2}+\dfrac{2}{2}\)
\(2x=\dfrac{3}{2}\)
\(x=\dfrac{3}{2}:2\)
\(x=\dfrac{3}{2}.\dfrac{1}{2}\)
\(x=\dfrac{3}{4}\)
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