a) x+x+2.x=76:2
b)2.x=x+14
c)2.x-3/5=3/4
d)3/5-2.x=1/4
júp mik voi mik dang gap.Thanks truoc
Những câu hỏi liên quan
tim gia tri cua bien thoa man mot dieu kien cho truoc
1) (x-2)^3-(x-3)*(x^2+3x+9)+6(x+1)^2=49
2) x(x+5)(x-5)-(x+2)(x^2-2x+4)=42
3) (x+3)^3-(x+1)^3=56
4) (3x-5)(5-3x)+9(x+1)^2=30
5) x(x+5)(x-5)-(x+2)(x^2-2x+4)=42
HO MIK VS A CAM ON MN
day mik cach lam dang nay voi cac ban
tim a va b sao cho
(x3 +ax2-3x+b) :(x-2) du 5 va : (x-1) du -4
GIÚP MÌNH VỚI Ạ!
a) 4/9 + 4/3x = 7/9
b) (5/2 - x).(-4/7) = 9/14
c) 3x + 3/4 = 2\(\frac{2}{3}\)
d) -5/6 - x = 7/12 + -1/3
CÁC BẠN NÀO GIÚP ĐƯỢC THÌ MIK CẢM ƠN Ạ !!!
a: =>4/3x=7/9-4/9=1/3
=>x=1/4
b: =>5/2-x=9/14:(-4/7)=-9/8
=>x=5/2+9/8=29/8
c: =>3x+3/4=8/3
=>3x=23/12
hay x=23/36
d: =>-5/6-x=7/12-4/12=3/12=1/4
=>x=-5/6-1/4=-10/12-3/12=-13/12
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\(d,-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)
\(\Leftrightarrow-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-4}{12}\)
\(\Leftrightarrow-\dfrac{5}{6}-x=\dfrac{1}{4}\)
\(\Leftrightarrow-x=-\dfrac{5}{6}-\dfrac{1}{4}\)
\(\Leftrightarrow-x=-\dfrac{13}{12}\)
\(\Leftrightarrow x=\dfrac{13}{12}\)
\(c,3x+\dfrac{3}{4}=2\dfrac{2}{3}\)
\(\Leftrightarrow3x+\dfrac{3}{4}=\dfrac{8}{3}\)
\(\Leftrightarrow3x=\dfrac{8}{3}-\dfrac{3}{4}\)
\(\Leftrightarrow3x=\dfrac{23}{12}\)
\(\Leftrightarrow x=\dfrac{23}{12}:3\)
\(\Leftrightarrow x=\dfrac{23}{36}\)
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giup mik voi!!
a) 3^x+x^2=1
b) (3x-14)^n=1
c) (5^2x.5^x+1):5=125
3^x+3^x+1+3^x+2=243.39
a. 3^x=1-x^2
x=0 la nghiem
x>=1; VT>=3 VP<=0 vo nghiem
b. (de bai thieu n khac 0 vi neu n=0 dung voi moi x)
3x-14=1=> x=5
c.(5^2x5^x+1)=5^4
5^x+1=5^2=> x=1
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a] 1/3 + 4/3 x 1/2
b] x : 2/5 = 1/6 + 2/3
Chi tiết giúp mik nha
1/2+2/3 = 3/3 = 1
x : 2/5 = 5/6
x = 5/6x2/5
x = 1/3
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\(\dfrac{1}{2}+\dfrac{2}{3}=\dfrac{3}{3}=1\)
x : \(\dfrac{2}{5}\) = \(\dfrac{5}{6}\)
x = \(\dfrac{5}{6}\)x\(\dfrac{2}{5}\)
x = \(\dfrac{1}{3}\)
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thực hiện phép tính :
a) 5x+10/10xy^2 nhân 12x/x+2
b) x-4/3x-1 nhân 9x-3/x^2-16
c)4x+2/(x+4)^2/ chia 3(x+3)/x+4
d)5x-5/3x+3 chia x-1/x+1
a: \(=\dfrac{5\left(x+2\right)}{10xy^2}\cdot\dfrac{12x}{x+2}=\dfrac{60x}{10xy^2}=\dfrac{6}{y^2}\)
b: \(=\dfrac{x-4}{3x-1}\cdot\dfrac{3\left(3x-1\right)}{\left(x-4\right)\left(x+4\right)}=\dfrac{3}{x+4}\)
c: \(=\dfrac{2\left(2x+1\right)}{\left(x+4\right)^2}\cdot\dfrac{\left(x+4\right)}{3\left(x+3\right)}=\dfrac{2\left(2x+1\right)}{3\left(x+3\right)\left(x+4\right)}\)
d: \(=\dfrac{5\left(x-1\right)}{3\left(x+1\right)}\cdot\dfrac{x+1}{x-1}=\dfrac{5}{3}\)
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tìm x biết:
a) x - 3= (3 - x)^2
b) x^3 + 3/2x^2 + 3/4x + 1/8 = 1/64
c) 8x^3 - 50x = 0
d) (x - 2) (x^2 + 2x + 7) + 2(x^2 - 4) - 5(x - 2) = 0
e) x(x + 3) - x^2 - 3x = 0
f) x^3 + 27 + (x + 3) (x - 9) = 0
Giúp mik vs ạ
a) Ta có: \(\left(x-3\right)=\left(3-x\right)^2\)
\(\Leftrightarrow\left(x-3\right)^2-\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)
b) Ta có: \(x^3+\dfrac{3}{2}x^2+\dfrac{3}{4}x+\dfrac{1}{8}=\dfrac{1}{64}\)
\(\Leftrightarrow x^3+3\cdot x^2\cdot\dfrac{1}{2}+3\cdot x\cdot\dfrac{1}{4}+\left(\dfrac{1}{2}\right)^3=\dfrac{1}{64}\)
\(\Leftrightarrow\left(x+\dfrac{1}{2}\right)^3=\left(\dfrac{1}{4}\right)^3\)
\(\Leftrightarrow x+\dfrac{1}{2}=\dfrac{1}{4}\)
hay \(x=-\dfrac{1}{4}\)
c) Ta có: \(8x^3-50x=0\)
\(\Leftrightarrow2x\left(4x^2-25\right)=0\)
\(\Leftrightarrow x\left(2x-5\right)\left(2x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{5}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\)
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e) Ta có: \(x\left(x+3\right)-x^2-3x=0\)
\(\Leftrightarrow\left(x+3\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=1\end{matrix}\right.\)
f) Ta có: \(x^3+27+\left(x+3\right)\left(x-9\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(x^2-3x+9\right)+\left(x+3\right)\left(x-9\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(x^2-2x\right)=0\)
\(\Leftrightarrow x\left(x-2\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-3\end{matrix}\right.\)
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Thực hiện phép tính ( theo hằng đẳng thức đáng nhớ )
1. ( x - 2 ) mũ 2 - ( x + 3 ) mũ 2 + ( x+ 4 ) ( x-4 )
2. 2 ( 3x - 2 ) mũ 2 - 3 ( 2x + 5 ) mũ 2 - 6 ( x -1 ) ( x+ 1 )
3. ( 2x + 3 ) mũ 2 - 2 ( 2x + 3 ) ( 2x + 5 ) + ( 2x + 5 ) mũ 2
4. ( a + 1 ) ( a + 2 ) ( a mũ 2 + 4 ) ( a - 1 ) ( a mũ 2 + 1 ) ( a - 2 )
5. ( a + 2b - 3c - d ) ( a + 2b + 3c + d ) - ( a mũ 2 + 4ab + 4b mũ 2 )
Các bạn có thể giúp mik đc ko, mik cảm ơn các bạn nhiều !!!!
Đọc tiếp
Thực hiện phép tính ( theo hằng đẳng thức đáng nhớ )
1. ( x - 2 ) mũ 2 - ( x + 3 ) mũ 2 + ( x+ 4 ) ( x-4 )
2. 2 ( 3x - 2 ) mũ 2 - 3 ( 2x + 5 ) mũ 2 - 6 ( x -1 ) ( x+ 1 )
3. ( 2x + 3 ) mũ 2 - 2 ( 2x + 3 ) ( 2x + 5 ) + ( 2x + 5 ) mũ 2
4. ( a + 1 ) ( a + 2 ) ( a mũ 2 + 4 ) ( a - 1 ) ( a mũ 2 + 1 ) ( a - 2 )
5. ( a + 2b - 3c - d ) ( a + 2b + 3c + d ) - ( a mũ 2 + 4ab + 4b mũ 2 )
Các bạn có thể giúp mik đc ko, mik cảm ơn các bạn nhiều !!!!
bai 5 : tinh
a) tim x , biet (x+1) +(x+2 ) + ...+(x+100)=5750
b) chung minh rang B = 1/2^2 + 1/3^2 + 1/4^2 + ...+1/2021^2 < 1
giup mik luon voi
\(∘backwin\)
\(a ) ( x + 1 ) + ( x + 2 ) + ( x + 3 ) + ... + ( x + 100 ) = 5750\)
\( ( x + x + x + ... + x ) + ( 1 + 2 + 3 + ... + 100 ) = 5750 \)
\( 100 x + ( 1 + 100 ) ×100 : 2 = 5750\)
\(100 x + 5050 = 5750\)
\( 100 x = 5750 − 5050\)
\(100 x = 700\)
\(x = 700 : 100\)
\(x = 7\)
\(b,\) \(B=\)\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{2021^2}< \dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{2020}+2021\)
\( B < 1 -\)\(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{2020}-\dfrac{1}{2021}\)
\(B<1-\)\(\dfrac{1}{2021}\)
\(B<\)\(\dfrac{2020}{2021}\)
\(\dfrac{2020}{2021}< 1\)
\(B<1\)
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a) (x+1) +(x+2 ) + ...+(x+100)=5750
= 100x + (1+2+3+...+100) = 5750
=100x + 5050 = 5750
--> 100x = 5750-5050=700
--> x=7
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b) Ta thấy: 1/2^2 < 1/2.3
1/3^2 < 1/3.4
...
1/2021^2 < 1/2021.2022
--> B=1/2^2 + 1/3^2 + 1/4^2 + ...+ 1/2021^2 < 1/2.3 + 1/3.4 + ... +1/2021.2022 (1)
Ta có: 1/2.3 + 1/3.4 + ... +1/2021.2022
=1/2 - 1/3 + 1/3 - 1/4 + ... + 1/2021 - 1/2022
=1/2 - 1/2022 < 1 (2)
Từ (1) và (2) --> B<1 (đpcm)
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