Đặt \(B=4^{2023}+4^{2022}+\cdots+4^2+5\)

=>\(B=4^{2023}+4^{2022}+\cdots+4^2+4+1\)

=>\(4B=4^{2024}+4^{2023}+\cdots+4^3+4^2+4\)

=>\(4B-B=4^{2024}+4^{2023}+\cdots+4^3+4^2+4-4^{2023}-4^{2022}-\cdots-4^2-4-1\)

=>\(3B=4^{2024}-1\)

Ta có: \(A=75\cdot\left(4^{2023}+4^{2022}+\cdots+4^2+5\right)+25\)

\(=3\cdot25\cdot\left(4^{2023}+4^{2022}+\cdots+4^2+4+1\right)+25\)

\(=25\cdot3B+25=25\left(3B+1\right)=25\cdot4^{2024}\) ⋮\(4^{2024}\)

cách này là hữu ích nhất, còn có 1 cacnhs nữa là xét mod nhưng rất dài dòng và khó phát hiện nữa !

Đây là một hằng đẳng thức tổng quát bạn ơi,

\(a^{2k+1}+b^{2k+1}=\left(a+b\right)\left(a^{2k}+a^{2k-1}b+a^{2k-2}b^2+...+a^2b^{2k-2}+ab^{2k-1}+b^{2k}\right)\)Từ đó ta có: \(a^{2k+1}+b^{2k+1}⋮a+b\)

1 + 2 + 3 +...+ 50

Dãy trên có số số hạng là:

\(\left(50-1\right)+1=50\) (số)

Tổng của chúng là:

\(\frac{\left(50+1\right)\cdot50}{2}=1275\)

Vậy tổng của chúng là 1275

~Học tốt~

=1275

45-41+16=17

tick nhé

45-41+16=4+16=20 tick mk nha bn

= ( 2380 + 9 x 480) : 25 - 3500 : 25 

= ( 2380 + 4320 - 3500 ) : 25 

= 3200 : 25 

= 128

a: \(-145\cdot\left(13-57\right)+57\left(10-145\right)\)

\(=-145\cdot13+145\cdot57+57\cdot10-57\cdot145\)

\(=-145\cdot13+57\cdot10\)

=-1885+570

=-1315

b: \(17\left(15-16\right)+16\left(17-20\right)\)

\(=17\cdot15-17\cdot16+16\cdot17-16\cdot20\)

\(=17\cdot15-16\cdot20=255-320=-65\)

c: \(-38\left(25-4\right)+25\left(-4+38\right)\)

\(=-38\cdot25+38\cdot4-25\cdot4+25\cdot38\)

\(=38\cdot4-25\cdot4=4\cdot13=52\)

a/ \(\lim\limits_{x\rightarrow3}\dfrac{\sqrt[3]{x^2-1}-2}{x-3}+\lim\limits_{x\rightarrow3}\dfrac{2-\sqrt[4]{1+5x}}{x-3}\)

\(=\lim\limits_{x\rightarrow3}\dfrac{x^2-1-8}{\left(x-3\right)\left(\sqrt[3]{\left(x^2-1\right)^2}+2.\sqrt[3]{x^2-1}+4\right)}+\lim\limits_{x\rightarrow3}\dfrac{16-1-5x}{\left(x-3\right)\left(\sqrt[4]{\left(1+5x\right)^3}+2\sqrt[3]{\left(1+5x\right)^2}+4.\sqrt[3]{1+5x}+8\right)}\)

\(=\lim\limits_{x\rightarrow3}\dfrac{\left(x-3\right)\left(x+3\right)}{\left(x-3\right)\left(\sqrt[3]{\left(x^2-1\right)^2}+2.\sqrt[3]{x^2-1}+4\right)}+\lim\limits_{x\rightarrow3}\dfrac{-5\left(x-3\right)}{\left(x-3\right)\left(\sqrt[4]{\left(1+5x\right)^3}+2\sqrt[3]{\left(1+5x\right)^2}+4\sqrt[3]{1+5x}+8\right)}\)

\(=\dfrac{3+3}{\sqrt[3]{\left(3^2-1\right)^2}+2.\sqrt[3]{3^2-1}+4}-\dfrac{5}{\sqrt[4]{\left(1+5.3\right)^3}+2\sqrt[3]{\left(1+5.3\right)^2}+4.\sqrt[3]{1+5.3}+8}=\dfrac{11}{32}\)

\(\Rightarrow a^2+b^2=1145\)

40/ 

\(L=\lim\limits_{x\rightarrow0}\dfrac{af\left(x\right)+b^n-b^n}{f\left(x\right)\left[\sqrt[n]{\left(af\left(x\right)+b^n\right)^{n-1}}+b.\sqrt[n]{\left(af\left(x\right)+b^n\right)^{n-2}}+....+b^{n-1}\right]}\)

\(L=\lim\limits_{x\rightarrow0}\dfrac{a}{\sqrt[n]{\left(af\left(x\right)+b^n\right)^{n-1}}+b.\sqrt[n]{\left(af\left(x\right)+b^n\right)^{n-2}}+...+b^{n-1}}\)

\(L=\lim\limits_{x\rightarrow0}\dfrac{a}{b^{n-1}+b^{n-1}++...+b^{n-1}}=\dfrac{a}{nb^{n-1}}\)