109 x 7 =?
A. 703
B. 763
C. 163
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\(a.\)
\(\Leftrightarrow x-5+x-7=-12.\)
\(\Leftrightarrow x=-12+-12\)
\(\Leftrightarrow x=-24\)
\(b.\)
\(\Leftrightarrow3x+2x=-109+44\)
\(\Leftrightarrow5x=-65\)
\(\Rightarrow x=-13\)
\(c.\)
\(\Leftrightarrow2x-10-15+5x=-109\)
\(\Leftrightarrow2x-5x=-109+15+10\)
\(\Leftrightarrow3x=-84\)
\(\Rightarrow x=-28\)
\(d.\)
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Bai 2 :
\(\hept{\begin{cases}x+y=7\\x-7=13\end{cases}\Leftrightarrow\hept{\begin{cases}x+y=7\\x=20\end{cases}}}\)
Thay x vào phương trình đầu ta có :
\(20+y=7\Leftrightarrow y=-13\)
Vậy \(\left\{x;y\right\}=\left\{20;-13\right\}\)
Thử \(20-13=7\); \(20-7=13\)( thỏa mãn )
a)5-(13-3x)=109-(32+109)
5-(13-3x)=-32
13-3x =37
3x =-24
3x =-6
a)5-(13-3x)=109-(32+109)
5-13+3x =109-32-109
-8+3x=-32
3x=-32-(-8)
3x=-24
x=-24:3
x=-8
b)|3x-6|+(x-22)=0
(3x-6)+(x-22)=0
3x-6+x-22=0
3x+x=0+6+22
4x=10
x=\(\dfrac{5}{2}\)
c)/7-2x/=-13-5.(-8)
|7-2x|=27
⇒7-2x=27 hoặc 7-2x=-27
x=-10 hoặc x=-17
\(a)\)\(\left(111-x\right)+7^2=149\)
\(\Leftrightarrow\)\(\left(111-x\right)+49=149\)
\(\Leftrightarrow\)\(\left(111-x\right)=149-49\)
\(\Leftrightarrow\)\(111-x=100\)
\(\Leftrightarrow\)\(x=111-100\)
\(\Leftrightarrow\)\(x=11\)
\(b)\)\(\left|x\right|+18=163+\left(-45\right)\)
\(\Leftrightarrow\)\(\left|x\right|+18=163-45\)
\(\Leftrightarrow\)\(\left|x\right|+18=118\)
\(\Leftrightarrow\)\(\left|x\right|=118-18\)
\(\Leftrightarrow\)\(\left|x\right|=100\)
\(\Leftrightarrow\)\(x=100\)
\(\text{a)}350:\left[19-\left(7x-3\right)\right]=350\)
\(\Rightarrow19-\left(7x-3\right)=1\)
\(\Rightarrow19-7x+3=1\)
\(\Rightarrow-7x=-21\)
\(\Rightarrow x=3\)
\(\text{b)}7.\left[109-\left(x-9\right)\right]-420=0\)
\(\Rightarrow7\left(109-x+9\right)=420\)
\(\Rightarrow118-x=60\)
\(\Rightarrow x=58\)
\(\text{c)}252-2\left\{200-4\left[90-7.\left(19-9\right)\right]\right\}.x=4\)
\(\Rightarrow2\left\{200-4\left[90-7.10\right]\right\}.x=250\)
\(\Rightarrow\left[200-4\left(90-70\right)\right].x=125\)
\(\Rightarrow\left[200-4.20\right].x=125\)
\(\Rightarrow120x=125\)
\(\Rightarrow x=\frac{125}{120}=\frac{25}{24}\)
\(\text{Xin điểm ạ}\)
350:[19-(7x-3)]=350
[19-(7x-3)]=350:350
[19-(7x-3)]=1
(7x-3)=19-1
(7x-3)=18
7x=18+3
7x=21
x=21:7
x=3
vậy x=3
7.[109-(x-19)]-420=0
7.[109-(x-19)]=0+420
7.[109-(x-19)]=420
[109-(x-19)]=420:7
[109-(x-19)]=60
(x-19)=109-60
(x-19)=49
x=49+19
x=58
vậy x=58
254-2{200-4.[90-7.(19-9)]}.x=4
254-2{200-4.[90-7.10]}.x=4
254-2{200-4.[90-70]}.x=4
254-2{200-4.20}.x=4
254-2{200-80}.x=4
254-2.120.x=4
254-240.x=4
240.x=254-4
240.x=250
x=250:240
x=25/24
vậy x=25/24
Đáp án B