\(76-\left\{2\cdot\left[2\cdot5^2-\left(31-2\cdot3\right)\right]\right\}\)

\(=76-\left\{2\cdot\left[2\cdot25-\left(31-6\right)\right]\right\}\)

\(=75-\left[2\cdot\left(50-25\right)\right]\)

\(=76-\left(2\cdot25\right)\)

\(=76-50\)

\(=26\)

____________________

\(6^2\cdot10:\left\{780:\left[10^3-\left(2\cdot5^3+35\cdot14\right)\right]\right\}\)

\(=36\cdot10:\left\{780:\left[1000-\left(2\cdot125+490\right)\right]\right\}\)

\(=360:\left\{780:\left[1000-\left(250+490\right)\right]\right\}\)

\(=360:\left[780:\left(1000-740\right)\right]\)

\(=360:\left(780:260\right)\)

\(=360:3\)

\(=120\)

a: =76-{2*[2*25-31+6]}

=76-{2*[50-31+6]}

=76-2*25

=76-50=26

b: \(=360:\left\{\dfrac{780}{1000-2\cdot125-490}\right\}\)

\(=360:\dfrac{780}{260}\)

=360/3=120

Ta có: 3636:(12x−91)=36

12x–91=3636:36

12x–91=101

12x=101+91

12x=192

x=192:12

x=16

Vậy x=16

440 + 2. (125 – x) = 546

2. (125 - x)=546 - 440

2. (125 - x)=106

125 - x=106 : 2

125 - x=53

x=125-53

x=72

a)\(x.3^{15}=3^{17}\)

   \(x=3^{17}:3^{15}\)

\(x=3^2=9\)

b) \(5^x=6^x\Leftrightarrow x=1;x=0\)

c) \(x^3=x^6\)

B2 ss

a)\(3^{45}=\left(3^3\right)^{15}=27^{15}\)

   \(4^{30}=\left(4^2\right)^{15}=16^{15}\)

vì 16¹⁵ < 27¹⁵ nên 4³⁰ < 3⁴⁵

b) 

\(818.820=\left(819-1\right)\left(819+1\right)=819^2-1\)

vì 819² > 819² - 1 nên 819² > 818.820

cíu em với

vào chát riêng đi

\(x\cdot10-x+3\cdot x-9\cdot x\)

\(=x\left(10-1+3-9\right)\)

\(=x\left(9-9+3\right)=3x\)

\(x.3^{15}=3^{17}\)

\(x=3^{17}:3^{15}\)

\(x=3^{17-15}\)

\(x=3^2\)

\(x=9\)

Cái câu : \(5^x=6^x\) mình thày sai đề sao đó

các bạn giúp mình với

Viết rõ đầu bài ra đi em . chứ nhìn ko hiểu j cả

\(B=3^2+3^3+...+3^{99}\)

\(3B=3^3+3^4+...+3^{100}\)

\(3B-B=\left(3^3+3^4+...+3^{100}\right)-\left(3^2+3^3+...+3^{99}\right)\)

\(2B=3^{100}-3^2\)

\(B=\frac{3^{100}-9}{2}\)

\(2B+9=3^{2n+4}\)

\(\Leftrightarrow3^{2n+4}=3^{100}\)

\(\Leftrightarrow2n+4=100\)

\(\Leftrightarrow n=48\).