$B=1+5+5^2+5^3+...+5^{50}$
$\Rightarrow 5B=5+5^2+5^3+...+5^{50}$
$\Rightarrow 5B-B=4B=\left(5+5^2+5^3+...+5^{51}\right)-\left(1+5+5^2+5^3+...+5^{50}\right)$
$\Rightarrow 4B=5^{51}-1$
$\Rightarrow B=\frac{5^{51}-1}{4}$

đặt A = 1+5+5²+5³+...+5²⁰²¹+5²⁰²²

    5A = 5+5²+5³+...+5²⁰²²+5²⁰²³

    5A-A = (5+5²+5³+...+5²⁰²²+5²⁰²³)-(1+5+5²+5³+...+5²⁰²¹+5²⁰²² )

    4A = 5+5²+5³+...+5²⁰²²+5²⁰²³-1-5-5²-5³-...-5²⁰²¹-5²⁰²²

    4A = 5²⁰²³-1

      A = \(\dfrac{5^{2023}-1}{4}\)

4

x=8

x = 8

chiều cao của hình hộp chữ nhật là

            1500 : 120 = 12.5 (cm)

           đs.........

chiều cao của hình hộp chữ nhật là

            1500 : 120 = 12.5 (cm)

           đs.........

\(64=8^2;0,09=\left(0,3\right)^2;13=\sqrt{13}^2;x=\left(\sqrt{x}\right)^2\)

\(\dfrac{1}{4}=\left(\dfrac{1}{2}\right)^2;\dfrac{49}{81}=\left(\dfrac{7}{9}\right)^2;x^2=\left(x\right)^2;m^4=\left(m^2\right)^2\)

(-2/3x-3/5)(-3/2-10/3)=2/5

= (-2/3x-3/5) . ( -29/6 ) = 2/5

= (-2/3x-3/5) = 2/5 : ( -29/6 )

= -2/3x-3/5 = -12/145

= -2/3 x = -12/145 + 3/5

= -2/3 x = 15/29

= x = 15/29 : ( -2/3 )

= x = -45/58 

\(-\dfrac{2}{3}x-\dfrac{3}{5}=\dfrac{2}{5}:\dfrac{-29}{6}=-\dfrac{145}{12}\Leftrightarrow x=\left(-\dfrac{145}{12}+\dfrac{3}{5}\right):\left(-\dfrac{2}{3}\right)=\dfrac{689}{40}\)

5².125.(2,5)^-5.0,04

=5².5³.\(\dfrac{32}{3125}\).\(\dfrac{4}{100}\)

=5⁵.\(\dfrac{32}{5^5}\).\(\dfrac{1}{25}\)

= \(\dfrac{32}{25}\)

32/25