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a, \(\left(2x+7\right)^4=10^{11}:10^7\)
\(\Rightarrow\left(2x+7\right)^4=10^4\)
\(\Rightarrow2x+7=10\)
\(\Rightarrow2x=10-7\)
\(\Rightarrow2x=3\)
\(\Rightarrow x=\dfrac{3}{2}\) hay \(x=1,5\)
b, \(5^{x-1}.7^{x-1}=25.49\)
\(\Rightarrow\)\(5^{x-1}.7^{x-1}=5^2.7^2\)
\(\Rightarrow\left\{{}\begin{matrix}5^{x-1}=5^2\\7^{x-1}=7^2\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x-1=2\\x-1=2\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=3\\x=3\end{matrix}\right.\)
c, \(\left(x-5\right)^{2018}=9.\left(x-5\right)^{2016}\)
\(\Rightarrow\dfrac{\left(x-5\right)^{2018}}{\left(x-5\right)^{2016}}=9.\dfrac{\left(x-5\right)^{2016}}{\left(x-5\right)^{2016}}\)
\(\Rightarrow\left(x-5\right)^2=9\)
\(\Leftrightarrow\left(x-5\right)^2=3^2\)
\(\Rightarrow x-5=3\)
\(\Rightarrow x=3+5\)
\(\Rightarrow x=8\)
Tính
a) đáp án là 90
b)đáp án là âm 9
c)đáp án là âm 10
tìm x
a) xbằng 5
b) x bằng 3
c) x bằng 3
a) {[( 32 + 1 ) . 10 - ( 8 : 2 + 6 ) ] : 2 } + 55 -( 10 : 5 )3
= ( 10 . 10 - 10 : 2 ) + 55 - 6
= 90 : 2 ) + 55 - 6
= 45 + 55 - 6
= 100 - 6
= 94
b) 100 - [ 60 - ( 9 - 2 )2 ] . 32
= 100 - [ 60 - 72 ] . 9
= 100 - [ 60 - 49 ] . 9
= 100 - 11 . 9
= 100 - 99
= 1
c) [ ( 1253 ) . 75 - ( 175 )5 : 5 ] : 20162017
= 0 : 20162017
= 0
+ bài d kg hiểu! Xin lỗi
a) \(\left(3^5\times3^7\right):3^{10}+5\times2^4-7^3:7=3^{12}:3^{10}+5\times2^4-7^2\)
\(=3^2-5\times16-7^2=9-80-49=-120\)
b) \(15:\left(3^5:3^4\right)-2^9:2^7=15:3-2^2=5-4=1\)
c)\(5\times3^5:\left(3^8:3^5\right)-2^3\times5=5\times3^5:3^3-2^3\times5\)
\(=5\times3^2-2^3\times5=5\times9-8\times5=45-40=5\)
a,71.2-6.(2x+5)=10^5:10^3
142-6.(2x+5)=10^2
142-6.(2x+5)=100
6.(2x+5)=142-100
6.(2x+5)=42
2x+5=42:6
2x+5=7
2x=7-5
2x=2
x=1
Vậy x=1
Trả lời :
a) 52. 54. 56 . 57 = 52 + 4 + 6 + 7 = 519
b) x5 . x4 . x . x7 . x6 = x5 + 4 + 1 + 7 + 6 = x23
c) 73 . 75 . 7 . 73 = 73 + 5 + 1 + 3 = 712
d) 510 : 54 = 510 - 4 = 56
e) a10 : a7 = a10 - 7 = a3
j) 815 : 815 = 815 - 15 = 80 = 1
g) 925 : 924 = 925 - 24 = 91 = 9
h) 710 : 72 = 710 - 2 = 78
\(5^9\cdot x=5^7\)
\(x=5^7-5^9\)
\(x=5^{^{ }-2}\)
b) là 10-2