5 la puterea 100-4*5 la puterea 99-4*5 la puterea 98-….-4*5
Dau coroana va rog repede!!!!

5¹⁰⁰-4(5⁹⁹+5⁹⁸+...+5)=5
[tex]{5}^{100} -4 \times ( 5\times \frac{5 {}^{99} - 1} {4})[/tex]
=
[tex] {5}^{100} -4 \times ( \frac{ {5}^{100} - 5 }{4} )[/tex]
=
[tex] {5}^{100} - {5}^{100} + 5 = 5[/tex]
5¹⁰⁰-4*5⁹⁹-4*5⁹⁸-….-4*5
S=5+5²+...+5⁹⁸+5⁹⁹
5S=-5+(5+5²+5³+...+5⁹⁹+5¹⁰⁰)
5S=-5+S+5¹⁰⁰
4S=5¹⁰⁰-5
S=(1/4)5¹⁰⁰-5/4