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Ta có \(5^x=125\)
\(\Rightarrow5^x=5^3\Rightarrow x=3\)
Vậy x = 3
b,\(3^{2x}=81\)
\(\Rightarrow3^{2x}=3^4\Rightarrow2x=4\Rightarrow x=2\)
Vậy x = 2
c,\(5^{2x-3}-2.5^2=5^2.3\)
\(\Rightarrow5^{2x-3}=5^2.3+5^2.2\Rightarrow5^{2x-3}=5^2.\left(2+3\right)\Rightarrow5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\Rightarrow2x=6\Rightarrow x=3\)
Vậy x = 3
78. 31 + 78. 24 +78.17 + 22.72
78. (31+24+17) + 22.72
78.72+ 22.72
(78+22) . 72
100.72
7200
21.\(7^2\)-11.\(7^2\)+ 49.125.16
21.49- 11.49+ 49.125.16
21.49-11.49+125.49.16
(21-11+125).49.16
145.49.16
7105.16
113680
a,(3x+5)2=289
=>(3x+5)2=172
=>3x+5=17
=>3x=12
=>x=4
b,x50=x
=>x50-x=0
=>x=1
c,2x.7=224
=>2x=224:7
=>2x=32
=>2x=25
=>x=5
#Koo#
\(a,2^{x+2}-2^x=96\)
\(=>2^x.2^2-2^x=96\)
\(=>2^x.\left(4-1\right)=96\)
\(=>2^x.3=96\)
\(=>2^x=96:3=32\)
\(=>2^x=2^5\)
\(=>x=5\)
\(b,720:\left[41.\left(2x-5\right)\right]=2^3.125:5^2\)
\(=>720:\left[41.\left(2x-5\right)\right]=8.125:25\)
\(=>720:\left[41.\left(2x-5\right)\right]=8.5=40\)
\(=>41.\left(2x-5\right)=720:40=18\)
\(=>2x-5=18:41=\frac{18}{41}\)
\(=>2x=\frac{18}{41}+5=\frac{223}{41}\)
\(=>x=\frac{223}{41}:2=\frac{223}{62}\)
\(c,\left(-2x+7\right)^{19}=\left(-2x+7\right)^{19}.\left(x+1\frac{1}{4}\right)^2\)
\(=>\left(-2x+7\right)^{19}:\left(-2x+7\right)^{19}=\left(x+\frac{5}{4}\right)^2\)
\(=>1=\left(x+\frac{5}{4}\right)^2\)
\(=>1^2=\left(x+\frac{5}{4}\right)^2\)
\(=>1=x+\frac{5}{4}\)
\(=>x=1-\frac{5}{4}=-\frac{1}{4}\)
Chúc bạn Hk tốt!!!!
Và giữ đúng lời hứa trên@@!!!!!
a, 52x - 3 - 2.52 = 52.3
=> 52x - 3 - 50 = 75
=> 52x - 3 = 125
=> 52x - 3 = 53
=> 2x - 3 = 3
=> 2x = 0
=> x = 0
vậy_
b, (x + 1) + (x + 2) + ....+ (x + 100) = 5750
=> x + 1 + x + 2 + ... + x + 100 = 5750
=> (x + x + x + ... + x) + (1 + 2 + 3 + ... + 100) = 5750
=> 100x + 5050 = 5750
=> 100x = 700
=> x = 7
vậy_
a) 32x = 81= 34
=> 2x = 4
x = 2
b) 52x-3 - 2.52 = 52.3
52x-3 = 125 = 53
=> 2x - 3 = 3
=> 2x = 6
x = 3
32x = 81
32x = 34
=> 2x = 4
x = 4 : 2
x = 2
52x-3 - 2.52 = 52.3
52x-3 - 2.25 = 25.3
52x-3 - 50 = 75
52x-3 = 75 + 50
52x-3 = 125
52x-3 = 53
=> 2x-3 = 3
2x = 3+3
2x = 6
x = 6 : 2
x = 3