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1) \(x-36:18=12\)
\(\Leftrightarrow x-2=12\)
\(\Rightarrow x=14\)
2) \(x-38:12=12\)
\(\Leftrightarrow x-\frac{19}{6}=12\)
\(\Rightarrow x=\frac{91}{6}\)
3) \(\left(25+x\right)-20:4=35\)
\(\Leftrightarrow25+x-5=35\)
\(\Leftrightarrow x=15\)
4) \(720:\left[41-\left(2x-5\right)\right]+8=48\)
\(\Leftrightarrow41-2x+5=18\)
\(\Leftrightarrow2x=28\)
\(\Rightarrow x=14\)
5) \(5x-x+15=223\)
\(\Leftrightarrow4x=208\)
\(\Rightarrow x=52\)
6) \(7x-55=2x\)
\(\Leftrightarrow5x=55\)
\(\Rightarrow x=11\)
7) \(\left(x-10\right).11=0\)
\(\Leftrightarrow x-10=0\)
\(\Rightarrow x=10\)
1) Ta có : a : 3 = 10
a = 10.3
a = 30
2) a) 8x-4x = 1208
=> 4x = 1208
x = 1208 : 4
x = 302
b) 75883 - (31200+x) = 999
31200+x = 75883 - 999
31200+x = 74884
x = 74884 - 31200
x = 43684
3) Ta có : x:5 = 234
x = 234.5
x = 1170
Vậy ta có tập hợp x = {1170}
4) Ta có : Hiệu số tự nhiên lớn nhất là : 321 - 102 = 219
Hiệu số tự nhiên nhỏ nhất là : 103 - 102 = 1
1)a = 3 x 10 = 30
=> a \(\in\)N và a = 30
2) A => x . (8 - 4) = 1208
=> x . 4 = 1208
=> x = 1208 : 4
=> x = 302
\(a,2x+15=27\)
\(\Rightarrow2x=27-15\)
\(\Rightarrow2x=12\)
\(\Rightarrow x=12\div2\)
\(\Rightarrow x=6\)
a)
5.(12-x)-20=30
⇒60-5x-20=30
⇒-5x=30+20-60
⇒-5x=-10
⇒x=2
b)(17x - 25 ) : 8 + 65 = 92
(17x - 25 ) : 8 + 65 = 81
17x - 25 = 16 x 8 = 128
17x = 128+25=153
x= 153:17 =9
c)
x=23
Giải thích các bước giải:
3x – 10 = 2x + 13
3x-2x=13+10
x=23
d)4(2x+7)-3(3x-2)=24
4.2x+4.7-3.3x+3.2=24
8x+28-9x+6=24
8x-9x=24-28-6=-10
=>(-1)x=-10
x=-10:(-1)
x=10
a. \(5\cdot\left(12-x\right)-20=30\Leftrightarrow5\left(12-x\right)=50\)
\(\Leftrightarrow12-x=50:5=10\)
\(\Leftrightarrow x=12-10=2\)
b. \(\left(17x-25\right):8+65=9^2\)
\(\Leftrightarrow\left(17x-25\right):8=81-65=16\)
\(\Leftrightarrow17x-25=16:8=2\)
\(\Leftrightarrow17x=2+25=27\Leftrightarrow x=\frac{27}{17}\)
c. \(3x-10=2x+13\)
\(\Leftrightarrow3x-2x=10+13\)
\(\Leftrightarrow x=23\)
d. \(4\cdot\left(2x+7\right)-3\cdot\left(3x-2\right)=24\)
\(\Leftrightarrow8x+28-9x+6=24\)
\(\Leftrightarrow34-x=24\Leftrightarrow x=10\)
75883 - (31200+x) = 999
=> 31200+x = 74884
=> x = 74884 - 31200
=> x = 43684
Bài làm :
\(a,115-4x=7\)
\(4x=115-7\)
\(4x=108\)
\(x=27\)
b, Sai đề bài rồi cậu ơi
\(c,25+3.\left(x-8\right)=106\)
\(3\left(x-8\right)=106-25\)
\(3\left(x-8\right)=81\)
\(x-8=27\)
\(x=27+8\)
\(x=35\)
\(d,3^x=81\)
\(3^x=3^4\)
\(\Rightarrow x=4\)
Học tốt
\(A=3x-x^2\)
\(=-\left(x^2-2.x.\frac{3}{2}+\left(\frac{3}{2}\right)^2-\frac{9}{4}\right)\)
\(=-\left(\left(x-\frac{3}{2}\right)^2-\frac{9}{4}\right)\)
\(=\frac{9}{4}-\left(x-\frac{3}{2}\right)^2\ge\frac{9}{4}\)
Min A = \(\frac{9}{4}\)khi \(x-\frac{3}{2}=0=>x=\frac{3}{2}\)
\(B=25+2x-x^2\)
\(=-\left(x^2-2x+1-26\right)\)
\(=-\left(\left(x-1\right)^2-26\right)\)
\(=26-\left(x-1\right)^2\ge26\)
Min A = 26 khi \(x-1=0=>x=1\)
\(C=x^2-5x+19\)
\(=x^2-2.x.\frac{5}{2}+\left(\frac{5}{2}\right)^2+\frac{51}{4}\)
\(=\left(x+\frac{5}{2}\right)^2+\frac{51}{4}\ge\frac{51}{4}\)
Min C = \(\frac{51}{4}\)khi \(x+\frac{5}{2}=0=>x=\frac{-5}{2}\)
@@@ nha các bạn . Thanks
a) \(8x-40=56\)
\(\Leftrightarrow8x=96\)
\(\Rightarrow x=12\)
b) \(105-3x=60\)
\(\Leftrightarrow3x=45\)
\(\Rightarrow x=15\)
c) \(75883-\left(31200+x\right)=999\)
\(\Leftrightarrow31200+x=74884\)
\(\Rightarrow x=43684\)
d) \(19-9\left(x+1\right)=10\)
\(\Leftrightarrow9\left(x+1\right)=9\)
\(\Leftrightarrow x+1=1\)
\(\Rightarrow x=0\)
e) \(\left(17x-25\right)\div8+65=81\)
\(\Leftrightarrow\left(17x-25\right)\div8=16\)
\(\Leftrightarrow17x-25=128\)
\(\Leftrightarrow17x=153\)
\(\Rightarrow x=9\)
a) 8x - 40 = 56
8x = 56 - 40
8x = 16
x = 2
b) 105 - 3x = 60
3x = 105 - 60
3x = 45
x = 15
c) 75883 - ( 31200 + x ) = 999
75883 - 31200 - x = 999
44683 - x = 999
x = 44683 - 999
x = 43684
d) 19 - 9 ( x + 1 ) = 10
19 - 9x - 9 = 10
10 - 9x = 10
9x = 0
x = 0
e) ( 17x - 25 ) : 8 + 65 = 81
( 17x - 25 ) : 8 = 16
17x - 25 = 128
17x = 128 + 25
17x = 153
x = 9