Tìm x: 2^x-3 + 2^x-2 + 2^x-1 = 448
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a) \(3x4^{x+1}-5.4^x=448\)
\(\Leftrightarrow4^x\left(3x4-5\right)=448\)
\(\Leftrightarrow4^x.7=448\)
\(\Leftrightarrow4^x=64=4^3\)
\(\Leftrightarrow x=3\)
b) \(5.\left(x-2\right)^3=4^3+71\left(x>1\right)\)
\(\Leftrightarrow5.\left(x-2\right)^3=64+71\)
\(\Leftrightarrow5.\left(x-2\right)^3=135\)
\(\Leftrightarrow\left(x-2\right)^3=27=3^3\)
\(\Leftrightarrow x-2=3\)
\(\Leftrightarrow x=5\)
1 000 000 x 2 x 4 x 8 x 16 x 32 x 64 x 128 x 256 x 512 x 1024 x 2048 x 4096 x 8192=10000000248163264
\(a)\)
\(y\times15-y\times25+y\times15=3780-255\)
\(y\times15-y\times25+y\times15=3525\)
\(y\times\left(15-25+15\right)=3525\)
\(y\times5=3525\)
\(y=3525:5\)
\(y=705\)
\(b)\)
\(341 + 448 : y - 141 = 214\)
\(341 + 448 : y = 214+141\)
\(341 + 448 : y = 355\)
\(448:y=355-341\)
\(448:y=14\)
\(y=448:14\)
\(y=32\)
a) \(-x+821+534=499+\left(x-84\right)\)
\(-x-x=499-84-821-534\)
\(-2x=-940\)
\(x=470\)
b) \(x-96=\left(448-x\right)-150\)
\(x+x=448-150+96\)
\(2x=394\)
\(x=197\)
c) \(-\left(754+x\right)=\left(x-12-741\right)-23\)
\(-754-x=x-12-741-23\)
\(-x+x=-12-741-23+754\)
\(0x=2\)
\(x\)ko tồn tại
d) \(\left(6+x\right)-\left(17-21\right)=-25\)
\(6+x-17+21=-25\)
\(x=-25-6+17-21\)
\(x=-35\)
e) \(17-\left(x+2\right)=3\)
\(17-x-2=3\)
\(-x=3-17+2\)
\(-x=-12\)
\(x=12\)
h) \(-10-\left(31-x\right)=40\)
\(-10-31+x=40\)
\(x=40+10+31\)
\(x=81\)
k mk nha bạn
\(2^{x+1}+2^{x+2}+2^{x+3}=448\)
=>\(2^x.2+2^x.4+2^x.8=448\)
=>\(2^x\left(2+4+8\right)=448\)
=>\(2^x=32\)
=>\(2^x=2^5\)
=>\(x=5\)
Vậy...
ta có : \(2^{x+1}+2^{x+2}+2^{x+3}=448\) \(\Leftrightarrow2^{x+1}\left(1+2+2^2\right)=448\)
\(\Leftrightarrow2^{x+1}\left(1+2+4\right)=448\Leftrightarrow2^{x+1}.7=448\Leftrightarrow2^{x+1}=\dfrac{448}{7}\)
\(\Leftrightarrow2^{x+1}=64\Leftrightarrow2^{x+1}=2^6\Rightarrow x+1=6\Leftrightarrow x=6-1=5\)
vậy \(x=5\)
\(m_{b1\uparrow}=m_{H_2O}=1,8\left(g\right)\Rightarrow n_{H_2O}=0,1\left(mol\right)\)
=> \(n_H=0,2\left(mol\right)\)
\(m_{b2\uparrow}=m_{CO_2}=3,52\left(g\right)\Rightarrow n_{CO_2}=0,08\left(mol\right)\)
=> \(n_C=0,08\left(mol\right)\)
\(n_{N_2}=0,02\left(mol\right)\Rightarrow n_N=0,04\left(mol\right)\)
Ta có : \(m_O=3-\left(0,08.12+0,2+0,04.14\right)=1,28\left(g\right)\)
=> \(n_O=0,08\left(mol\right)\)
\(M_X=2,586.29=75\)
Đặt CT của X là CxHyOzNt (x,y,z,t >0)
Ta có : \(x:y:z:t=0,08:0,2:0,08:0,04=2:5:2:1\)
=> CTĐGN : \(\left(C_2H_5O_2N\right)_n\)
Ta có : 75n=75
=> n=1
Vậy CTPT của X là C2H5O2N
( x + 135 ) : 1 = 448
x+ 135 = 448 x 1
x + 135 = 448
x = 448 - 135
x = 313