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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) \(\left(x-10\right).11=0\)
\(\Leftrightarrow x-10=0\)
\(\Rightarrow x=10\)
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. \(4\cdot\left(2x+7\right)-3\cdot\left(3x-2\right)=24\)
\(\Leftrightarrow8x+28-9x+6=24\)
\(\Leftrightarrow34-x=24\Leftrightarrow x=10\)
b2
P=4a^2 + 4a =4(a^2 + a)=4.[a.a + a]=4[a.(a+1)]
Mà a và a+1 là 2 số nguyên liên tiếp nên tích 2 số này chia hết cho 2
Đặt a(a+1)=2.k ( k thuộc Z)
Suy ra: P=4.2k=8k chia hết cho 8
k ch mình nha
a) \(\left(17x-25\right):8+65=9^2\)
\(\left(17x-25\right).\frac{1}{8}+65=81\)
\(\frac{17}{8}x-\frac{25}{8}=81-65\)
\(\frac{17}{8}x-\frac{25}{8}=16\)
\(\frac{17}{8}x=16+\frac{25}{8}\)
\(\frac{17}{8}x=\frac{128}{8}+\frac{25}{8}\)
\(\frac{17}{8}x=\frac{153}{8}\)
\(x=\frac{153}{8}:\frac{17}{8}\)
\(x=\frac{153}{8}.\frac{8}{17}\)
\(x=\frac{153}{17}\)
\(x=9\)
vay \(x=9\)
b) \(80-\left(4.5^2-3.2^3\right)=2^{10}-\left(x-4\right)\)
\(80-\left(100-24\right)=1024-x+4\)
\(80-76=1028-x\)
\(x=1028-80+76\)
\(x=1024\)
vay \(x=1024\)
\(=\left(2x+\frac{3}{4}\right)\frac{7}{9}=\frac{15}{8}\)
\(=2x+\frac{3}{4}\)\(=\frac{15}{8}:\frac{7}{9}\)
=\(2x+\frac{3}{4}=\frac{135}{56}\)
=2x=\(\frac{135}{56}-\frac{3}{4}\)
=2x=\(\frac{93}{56}\)
x=\(\frac{93}{56}:2\)
x=\(\frac{93}{112}\)
k nha
7.( x-6 )= 4x +9
=> 7x - 42 - 4x = 9
=> 3x = 51
=> x = 17
a) \(\left(x-9\right)^4=\left(x-9\right)^7\)
\(\Rightarrow\left[{}\begin{matrix}x-9=1\\x-9=0\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=10\\x=9\end{matrix}\right.\)
b) \(\left(3x-15\right)^{10}=\left(3x-15\right)^{15}\)
\(\Rightarrow\left[{}\begin{matrix}3x-15=0\\3x-15=1\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{15}{3}\\x=\dfrac{16}{3}\end{matrix}\right.\)
c) \(\left(x-8\right)^3=\left(x-8\right)^6\)
\(\Rightarrow\left[{}\begin{matrix}x-8=0\\x-8=1\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=8\\x=9\end{matrix}\right.\)
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