a. X x 10 = 1000
b. X x 36 = 72
c. X+3+7=90
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\(a,x-36:18=12-15\\ \Rightarrow x-2=-3\\ \Rightarrow x=-1\\ b,92-\left(17+x\right)=72\\ \Rightarrow17+x=20\\ \Rightarrow x=3\\ c,720:\left[41-\left(2x+5\right)\right]=40\\ \Rightarrow41-\left(2x+5\right)=18\\ \Rightarrow2x+5=23\\ \Rightarrow2x=18\\ \Rightarrow x=9\\ d,\left(x+2\right)^3-23=41\\ \Rightarrow\left(x+2\right)^3=64\\ \Rightarrow\left(x+2\right)^3=4^3\\ \Rightarrow x+2=4\\ \Rightarrow x=2\)
a) 90/x - 36/x-6 = 2.
ĐKXĐ: x≠0, x≠6.
<=> 90(x-6)-36x-2x(x-6)=0
<=> 90x-540-36x-2x2+12x=0
<=> -2x2+66x-540=0
<=> \(\left[{}\begin{matrix}x=18\left(tm\right)\\x=15\left(tm\right)\end{matrix}\right.\)
b) 1/x+1/x+10=1/12
ĐKXĐ: x≠0
<=> 1/x+1/x+10-1/12=0
<=> 12+12+10.12x-x=0
<=> 12+12+120x-x=0
<=> 119x+24=0
<=> 119x=-24
<=> x= -24/119(tm)
a) 58.57+58.150-58.125
=58.(57+150-125)
=58. 82
= 4756
b)32.5-22.7+83.20190
=9.5-4.7+83
=45-28+83
=100
c)2019+(-247)+(-53)-2019
=(2019-2019)+[ (-247)+(-53)]
0+(-300)
= -300
d)13.70-50 [(19-32):2+23]
=13.70-50[10:2+8]
=13.70-50.13
=13.(70-50)
=13.20
=260
2.
a)x-36:18=12-5
x-36:18=6
x-36=6.18
x-36=108
x=108+36
x= 144
b)92-(17+x)=72
17+x=92-72
17+x=20
x=20-17
x=3
c)720:[41-(2x+5)]=40
41-(2x+5)=720:40
41-(2x+5)= 18
2x+5=41-18
2x+5=23
2x=23-5
2x=18
x=18:2
x=9
d) (x+2)3 -23=41
(x+2)3 =41+23
(x+2)3 =64
=> (x+2)3 =43
=>x+2=4
=>x=4-2
=>x=2
a: \(\Leftrightarrow\dfrac{x}{-4}=\dfrac{21}{y}=\dfrac{z}{-80}=\dfrac{3}{4}\)
=>x=-3; y=28; z=-60
b: 5/12=x/-72
=>x=-72*5/12=-6*5=-30
c: =>x+3=-5
=>x=-8
a, \(\frac{5}{x+7}+\frac{8}{2x+14}=\frac{3}{2}\) Đkxđ : \(x\ne-7\)
⇔ \(\frac{5}{x+7}+\frac{8}{2\left(x+7\right)}=\frac{3}{2}\)
⇔ \(\frac{10}{2\left(x+7\right)}+\frac{8}{2\left(x+7\right)}=\frac{3\left(x+7\right)}{2\left(x+7\right)}\)
⇒ \(10+8=3\left(x+7\right)\)
⇔ \(10+8=3x+21\)
⇔ \(-3x=21-10-8\)
⇔ \(-3x=3\)
⇔ \(x=-1\) ( tm )
Ptr có tập nhiệm : S \(=\left\{-1\right\}\)
b, \(\frac{x+3}{x-3}-\frac{1}{x}=\frac{3}{x\left(x-3\right)}\) Đkxđ : \(x\ne3;x\ne0\)
⇔ \(\frac{x\left(x+3\right)}{x\left(x-3\right)}-\frac{1\left(x-3\right)}{x\left(x-3\right)}=\frac{3}{x\left(x-3\right)}\)
⇒ \(x\left(x-3\right)-1\left(x-3\right)=3\)
⇔ \(x^2-3x-x+3=3\)
⇔ \(x^2-4x=0\)
⇔ \(x\left(x-4\right)=0\)
⇔ \(\left\{{}\begin{matrix}x=0\\x-4=0\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}x=0\left(ktm\right)\\x=4\left(tm\right)\end{matrix}\right.\)
Ptr có tập nhiệm : S \(=\left\{4\right\}\)
a) \(24\times y+76\times y=100\)
\(\Rightarrow\left(24+76\right)\times y=100\)
\(\Rightarrow100\times y=100\)
\(\Rightarrow y=100:100\)
\(\Rightarrow y=1\)
b) \(125\times y-100\times y=1000\)
\(\Rightarrow\left(125-100\right)\times y=1000\)
\(\Rightarrow25\times y=1000\)
\(\Rightarrow y=1000:25\)
\(\Rightarrow y=40\)
a)ĐKXĐ:x\(\ne\)0 x\(\ne\)6
=>90(x-6)-36x=2x(x-6)
<=>90x-540-36x=2x2-12x
<=>2x2-12x=54x-540
<=>2x2-66x+540=0
<=>x2-33x+270=0
<=>(x2-15x)-(18x-270)=0
<=>(x-15)(x-18)=0
<=>x=15(tm) hoặc x=18(tm)
b)ĐKXĐ:x\(\ne\)0 x\(\ne\)3
sai đề
c)ĐKXĐ:x\(\ne\)-2 x\(\ne\)2
=>3(x-2)-2(x+2)+8=0
<=>3x-6-2x-4+8=0
<=>x-2=0
<=>x=2(L)
Vậy PT vô nghiệm
d)ĐKXĐ: x\(\ne\)-7
=>10+8=\(\dfrac{3}{2}\)(câu này hình như đề cũng sai)
a
x=1000:10
x=100
b
x=72:36
x=2
c
x+10=90
x=90-10
x=80
X x 10=1000
x=1000:10
x=100
X + 3+7 =90
X +3 =90-7
X+3=83
X=83-3
X=80
X x 36=72
X=72:36
X=2