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a
=> \(x+2=\dfrac{484}{44}=11\)
=> x = 11 - 2 = 9
b
=> \(x+321=34.12=408\)
=> x = 408 - 321 = 87
c
=> \(x-210=246.15=3690\)
=> x = 3690 + 210 = 3900
d
=> \(205-x=\dfrac{420}{84}=5\)
=> x = 205 - 5 = 200
a: =>x+2=11
=>x=9
b: =>x+321=408
=>x=87
c: =>x-210=3690
=>x=3900
d: =>205-x=5
=>x=200
=> 320 : (x - 1) = 100 : 4 + 15
=> 320 : (x - 1) = 25 + 15
=> 320 : (x - 1) = 40
=> x - 1 = 320 : 40
=> x - 1 = 8
=> x = 8 + 1
=> x = 9
Cái này dễ
320:(x-1)=(125-25):4+15
320:(x-1)=100:4+15
320:(x-1)=25+15
320:(x-1)=40
x-1=320:40
x-1=8
x=8+1
=>x=9
a) \(\left|x\right|+2=2^3.\left(-2\right)^2\)
\(\Leftrightarrow\)\(\left|x\right|+2=32\)
\(\Leftrightarrow\)\(\left|x\right|=30\)
\(\Leftrightarrow\)\(x=\pm30\)
Vậy...
b) \(\left|x\right|+4=\left(-3\right)^2+\left(-2\right)\)
\(\Leftrightarrow\)\(\left|x\right|+4=7\)
\(\Leftrightarrow\)\(\left|x\right|=3\)
\(\Leftrightarrow\)\(x=\pm10\)
Vậy...
b2 :
a) 5 . ( -5 - 6 )
= 5 . ( -11 )
= -55
b) 321 + { - 15 + [ 30 + ( -321 ) ] }
= 321 + { - 15 + [ - 291 ] }
= 321 + ( - 306 )
= 15
19 . 92 - 9 . ( - 19 ) - 19
= 1748 - ( -171 ) - 19
= 1919 - 19
= 1900
1) \(2^3\times x-5^2\times x=2\times\left(5^2+2^2\right)-33\)
\(x\times\left(2^3-5^2\right)=2\times\left(25+4\right)-33\)
\(x\times\left(8-25\right)=2\times29-33\)
\(x\times-17=25\)
\(x=-\dfrac{25}{17}\)
2) \(15\div\left(x+2\right)=\left(3^3+3\right)\div1\)
\(15\div\left(x+2\right)=\left(27+3\right)\div1\)
\(15\div\left(x+2\right)=30\div1\)
\(15\div\left(x+2\right)=30\)
\(x+2=\dfrac{1}{2}\)
\(x=-\dfrac{3}{2}\)
3) \(20\div\left(x+1\right)=\left(5^2+1\right)\div13\)
\(20\div\left(x+1\right)=\left(25+1\right)\div13\)
\(20\div\left(x+1\right)=26\div13\)
\(20\div\left(x+1\right)=2\)
\(x+1=20\div2\)
\(x+1=10\)
\(x=9\)
4) \(320\div\left(x-1\right)=\left(5^3-5^2\right)\div4+15\)
\(320\div\left(x-1\right)=\left(125-25\right)\div4+15\)
\(320\div\left(x-1\right)=100\div4+15\)
\(320\div\left(x-1\right)=25+15\)
\(320\div\left(x-1\right)=40\)
\(x-1=8\)
\(x=9\)
5) \(240\div\left(x-5\right)=2^2\times5^2-20\)
\(240\div\left(x-5\right)=4\times25-20\)
\(240\div\left(x-5\right)=100-20\)
\(240\div\left(x-5\right)=80\)
\(x-5=30\)
\(x=35\)
6) \(70\div\left(x-3\right)=\left(3^4-1\right)\div4-10\)
\(70\div\left(x-3\right)=\left(81-1\right)\div4-10\)
\(70\div\left(x-3\right)=80\div4-10\)
\(70\div\left(x-3\right)=20-10\)
\(70\div\left(x-3\right)=10\)
\(x-3=7\)
\(x=10\)
1.a) 168 - 300 : 15
= 168 - 20 = 148
b) 103 - 13 = 90
2. 87 - (321 - x) = 75 : 5 = 15
321 - x = 87 - 15
321 - x = 72
x = 321 - 72 = 249
a, x = {45;60}
b, x = {35;42;49;56;63;70}
c, x = {36;54;72;90}
d, x = {36;48;60;72;84;96}
e, x = {25;30;35;40;45;50;55;60}
f, x = {27;30;33;36;39;42;45;48;51;54;57}
Đề có 1 chút lỗi nhỏ nhé, mình sửa lại luôn.
\(321⋮x\) và 15 < x < 320
\(321⋮x\Rightarrow x\inƯ\left(321\right)=\left\{\pm1;\pm3;\pm107;\pm321\right\}\)
Vì 15 < x < 320 \(\Rightarrow\) x = 107