a) 2x - 135 = 245 - 6x
b) 21x + 15 = 215 - 6x
c) \(\frac{x+2}{18}\)= \(\frac{-5}{9}\)
d) \(\frac{x+2}{-20}\)= \(\frac{-5}{x+2}\)
GIÚP MỊ ZỚI NHA!!!!! >.<
giải các pt sau
a)5X(X-2020)+X=2020
b)4(X-5)2-(2X+1)2=0
c)\(\frac{3X}{5}-\frac{2X+1}{3}=2-\frac{X-3}{15}\)
d)5X3+10X2+5X=0
e)2X3-8X=0
f)\(\frac{X^2+5}{25-X^2}=\frac{3}{X+5}+\frac{X}{X-5}\)
g)\(\frac{4}{2X-3}-\frac{4X}{9-4X^2}=\frac{1}{2X+3}\)
h)|2X-4|-15=1
i)20-3|2X+1|=17
k)|4X+2|-1,5=1
GIẢI GIÚP MÌNH NHANH VỚI NHA
\(5X\left(X-2020\right)+X=2020\)
\(\Leftrightarrow5X^2-10100X+X=2020\)
\(\Leftrightarrow5X^2-10099X=2020\)
\(\Leftrightarrow5X^2-10099X-2020=0\)
\(\Leftrightarrow5X^2-10100X+x-2020=0\)
\(\Leftrightarrow5X\left(X-2020\right)+X-2020=0\)
\(\Leftrightarrow\left(X-2020\right)\left(5X+1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=2020\\x=-\frac{1}{5}\end{cases}}\)
\(4\left(x-5\right)^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left[2\left(x-5\right)\right]^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left[2\left(x-5\right)-2x-1\right]\left[2\left(x-5\right)+2x+1\right]=0\)
\(\Leftrightarrow\left(2x-10-2x-1\right)\left(2x-10+2x+1\right)=0\)
\(\Leftrightarrow-11\left(4x-9\right)=0\)
\(\Leftrightarrow x=\frac{9}{4}\)
\(a,5x\left(x-2020\right)+x=2020\)
\(< =>5x\left(x-2020\right)+x-2020=0\)
\(< =>\left(5x+1\right)\left(x-2020\right)=0\)
\(< =>\orbr{\begin{cases}5x+1=0\\x-2020=0\end{cases}}\)
\(< =>\orbr{\begin{cases}5x=-1\\x=2020\end{cases}< =>\orbr{\begin{cases}x=-\frac{1}{5}\\x=2020\end{cases}}}\)
\(b,4\left(x-5\right)^2-\left(2x+1\right)^2=0\)
\(< =>4\left(x^2-20x+25\right)-\left(4x^2+4x+1\right)=0\)
\(< =>4x^2-80x+100-4x^2-4x-1=0\)
\(< =>-84x+99=0< =>84x=99< =>x=\frac{99}{84}\)
Tìm x
\(\frac{1}{x}-\frac{1}{2.x}-\frac{1}{6.x}-\frac{1}{12.x}-\frac{1}{20.x}-\frac{1}{30.x}=1\frac{5}{6}\)
Help me !!! Cần gấp ,giúp mị nha,mị cảm ơn nhìu :>
a)\(\sqrt{x^2+2x+10}+x^2+2x+8=0\)
b)\(15x-2x^2-5=\sqrt{2x^2-15x+11}\)
c)\(\sqrt{9x^2+45}+\sqrt{16x^2+80}+3\sqrt{\frac{x^2+5}{16}}-\frac{1}{4}\sqrt{\frac{25x^2+15}{9}}=9\)
d)\(3x^2+21x+18+2\sqrt{x^2+7x+7}=2\)
e)\(\sqrt{x^2+3x+2}-2\sqrt{2x^2+6x+2}=-\sqrt{2}\)
f)\(\sqrt{x-1}+\sqrt{x+3}-\sqrt{x^2+2x-3}-1=0\)
a) + \(VT=\sqrt{x^2+2x+10}+x^2+2x+1+7\)
\(=\sqrt{x^2+2x+1}+\left(x+1\right)^2+7>0\forall x\)
=> ptvn
d) ĐK : \(x^2+7x+7\ge0\)
Đặt \(t=\sqrt{x^2+7x+7}\ge0\) \(\Rightarrow t^2=x^2+7x+7\)
\(pt\Leftrightarrow3\left(x^2+7x+7\right)-3+2\sqrt{x^2+7x+7}-2=0\)
\(\Leftrightarrow3t^2+2t-5=0\Leftrightarrow\left(3t+5\right)\left(t-1\right)=0\)
\(\Leftrightarrow t=1\) ( do \(3t+5>0\forall t\ge0\) )
\(\Leftrightarrow x^2+7x+1=0\Leftrightarrow x^2+7x+6=0\)
\(\Leftrightarrow\left(x+1\right)\left(x+6\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=-6\end{matrix}\right.\) ( TM )
f) ĐK : \(x\ge1\)
Đặt \(\left\{{}\begin{matrix}a=\sqrt{x-1}\ge0\\b=\sqrt{x+3}\ge0\end{matrix}\right.\) thì pt trở thành :
\(a+b-ab-1=0\)
\(\Leftrightarrow\left(a-1\right)-b\left(a-1\right)=0\)
\(\Leftrightarrow\left(1-b\right)\left(a-1\right)=0\Leftrightarrow\left[{}\begin{matrix}a=1\\b=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\sqrt{x-1}=1\\\sqrt{x+3}=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\left(TM\right)\\x=-2\left(KTM\right)\end{matrix}\right.\)
Giải các phương trình sau:
a, 2x - 3 = 5x + 6
b, ( 2x + 1 ).( 3x - 2 ) = ( 5x - 8 ).( 2x + 1 )
c, \(\frac{2x+1}{3}-\frac{7x+5}{15}=\frac{2x-2}{5}\)
d,\(\frac{3x}{x-2}-\frac{x}{x-5}=\frac{3x}{\left(x-2\right).\left(5-x\right)}\)
e, ( x2 + 2x )2 + 9x2 + 18x + 20 = 0
Giúp ik a~
a , 2x -3 = 5x + 6
2x -5x=6+3
-3x = 9
x =9 :(-3)
x= -3
a) 2x-5x=3+6
-3x=9
x=-3
vậy........
b)(2x+1).(3x-2)-(5x-8).(2x+1)=0
(2x+1).(3x-2-2x-1)=0
(2x-1).(x-3)=0
==>x=1/2 ; x=3
c)(2x+1).5-(7x+5)=(2x-2).3
10x+5-7x-5=6x-6
3x=6x-6
3x-6x=6
-3x=6
x=-2
a) 2x - 3 = 5x + 6
<=> -3x = 9
<=> x = -3
b) (2x + 1).(3x - 2) = (5x - 8).(2x + 1)
<=> 6x2 - 4x + 3x - 2 = 10x2 + 5x - 16x -8
<=> -4x2 - 10x + 6 = 0
<=> \(\orbr{\begin{cases}x=\frac{1}{2}\\x=-3\end{cases}}\)
c) \(\frac{2\text{x}+1}{3}-\frac{7\text{x}+5}{15}=\frac{2\text{x}-2}{5}\)
<=> \(\frac{5.\left(2\text{x}+1\right)}{5.3}-\frac{7\text{x}+5}{15}=\frac{3.\left(2\text{x}-2\right)}{3.5}\)
<=> 10x + 5 - 7x + 5 - 6x + 6 = 0
<=> -3x + 16 = 0
<=> -3x = -16
<=> x = \(\frac{16}{3}\)
d) \(\frac{3x}{x-2}-\frac{x}{x-5}=\frac{3\text{x}}{\left(x-2\right).\left(5-x\right)}\)
<=> \(\frac{3\text{x}\left(x-5\right)-x\left(x-2\right)}{\left(x-2\right).\left(5-x\right)}=\frac{3\text{x}}{\left(x-2\right).\left(5-x\right)}\)
<=> 3x2 - 15x - x2 + 2x - 3x = 0
*Câu e dễ quá, bạn tự làm nhé :v*
Tìm các dãy tỉ số bằng nhau:
a) \(\frac{x}{4}=\frac{y}{3}=\frac{3}{9}\)và x-3y+4z=62
b) \(\frac{x}{y}=\frac{7}{20};\frac{y}{z}=\frac{5}{8}\)và 2x+5y-2z=100
c) \(\frac{x}{y}=\frac{9}{7};\frac{y}{z}=\frac{7}{3}\)và x-y+z=(-15)
d) \(\frac{6}{11}x=\frac{9}{2}y=\frac{18}{5}z\) và -x+y+z=(-120)
a: Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{4}=\dfrac{y}{3}=\dfrac{z}{9}=\dfrac{x-3y+4z}{4-3\cdot3+4\cdot9}=\dfrac{62}{31}=2\)
Do đó: x=8; y=6; z=18
b: Áp dụng tính chất của dãy tỉ số bằng nhau, ta đc:
\(\dfrac{x}{7}=\dfrac{y}{20}=\dfrac{z}{32}=\dfrac{2x+5y-2z}{2\cdot7+5\cdot20-2\cdot32}=\dfrac{100}{50}=2\)
Do đó: x=14; y=40; z=64
c: Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{9}=\dfrac{y}{7}=\dfrac{z}{3}=\dfrac{x-y+z}{9-7+3}=\dfrac{-15}{5}=-3\)
DO đó: x=-27; y=-21; z=-9
Tìm x, biết
a/ \(\frac{15}{x}-\frac{1}{3}=\frac{28}{51}\)
b/ \(\frac{x}{20}-\frac{2}{5}=10\)
c/ \(x+\frac{18}{23}=2\frac{1}{3}\)
d/ \(\frac{7}{11}< x-\frac{1}{7}< \frac{10}{13}\)
e/ \(\frac{7}{9}< \frac{13}{11}-x< \frac{15}{16}\)
Cho xin cách giải thik lun nha
a/ \(\frac{15}{x}-\frac{1}{3}=\frac{28}{51}\)
\(\frac{15}{x}=\frac{28}{51}+\frac{1}{3}\)
\(\frac{15}{x}=\frac{15}{17}\)
\(x=15:\frac{15}{17}\)
\(x=17\)
b) \(\frac{x}{20}-\frac{2}{5}=10\)
\(\frac{x}{20}=10+\frac{2}{5}\)
\(\frac{x}{20}=\frac{52}{5}\)
\(x=\frac{52}{5}\cdot20\)
\(x=208\)
c) \(x+\frac{18}{23}=2\frac{1}{3}\)
\(x+\frac{18}{23}=\frac{7}{3}\)
\(x=\frac{7}{3}-\frac{18}{23}\)
\(x=\frac{107}{69}\)
d) \(\frac{7}{11}< x-\frac{1}{7}< \frac{10}{13}\)
\(\Rightarrow\frac{7}{11}+\frac{1}{7}< x< \frac{10}{13}\)
\(\frac{60}{77}< x< \frac{60}{78}\)
Đến đây .....bí!
e) Tớ bỏ luôn đc ko.
D) 7/11<X-1/7<10/13
<=> 7/11+1/7<x< 10/13+1/7
<=> 60/77< x< 83/91
<=> 5460/1001 <x< 6391/1001
vậy X thuộc tập hợp các phÂN số lớn hơn 5460/1001 và bé hơn 913/1001
vd : Y/1001 trong đó y là 5461;5462;5463...6389;6390
e) 7/9<13/11-x<15/16
<=> 7/9-13/11<-x< 15/16 -13/11
<=> -40/99< -x< -43/176
<=> 43/99< x < 40/176( nhân với -1 nên đổi dấu )
<=> 387/1584 < x< 640/1584
<=> vậy X là các phân số có dạng y/1584 , trong đó Y là 388;389;390 ........ 639
Rút gọn biểu thức sau:
\(A=\left(\frac{x^2-2x}{2x^2+8}-\frac{2x^2}{8-4x+2x^2-x^3}\right)\left(1-\frac{1}{x}-\frac{2}{x^2}\right)\)
^ Giúp tui nhanh zới nha! ^
=[x(x-2)/2(x2+4)-2x2/(4+x2)(2-x)][x(x-2)(x+1)/x3]
={[x(x-2)(2-x)-4x2 ]/2(2-x)(4+x2)} .[x(x-2)(x+1)/x3 ]
=[-x(x2+4)/2(2-x)(4+x2)].[x(x-2)(x+1)/x3 ]
=-x.x(x-2)(x+1)/2(2-x)x3
=(x+1)/2x
Giải pt:
a) \(\frac{x^2+2x-16}{x^2-x-12}+1=\frac{2x+1}{x+3}+\frac{3x-8}{x-4}\)
b) \(\frac{2x-1}{x+2}+\frac{7x+9}{\left(x+2\right)\left(x-1\right)}=\frac{3x-1}{x-1}\)
c) \(\frac{x+1}{20}+\frac{x+2}{19}+\frac{x+3}{18}=\frac{x+20}{1}+\frac{x+19}{2}+\frac{x+18}{3}\)
Giải giúp mình với ạ :((
Giải các phương trình
a) \(\frac{2x}{x-1}+\frac{4}{x^2+2x-3}=\frac{2x-5}{x+3}\)
b)\(\frac{x^2-x}{x+3}-\frac{x^2}{x-3}=\frac{7x^2-3x}{9-x^2}\)
c)\(\frac{3}{4x-20}+\frac{15}{50-2x^2}+\frac{7}{6x+30}\)