chứng minh rằng:
\(19^{45}+10^{30}⋮20\)
chứng minh (19^45+19^30) chia hết cho 20
Chứng minh rằng:
7520=4510.530
Chứng minh rằng:
7520=4510.530
Chứng minh rằng:
7520=4510.530
4510.530
=(32.5)10.530
=(32)10.510.530
=320.540
=320.(52)20
=320.2520
=(3.5)20
=7520
Chứng minh rằng :
7520=4510.530
Chứng minh rằng : \(75^{20}=45^{10}\times5^{30}\)
Giúp mk với các bn ơi !!!!
\(75^{20}=45^{10}.5^{30}\)
\(45^{10}.5^{30}\)
=\(\left(3^2.5\right)^{10}.5^{10+20}\)
= \(\left(3^2\right)^{10}.5^{10}.5^{30}\)
= \(3^{20}.5^{40}\)
= \(3^{20}.\left(5^2\right)^{20}\)
= \(3^{20}.25^{20}\)
= \(75^{20}\)
Chứng minh rằng:
7520=4510.530
4510.530=320.510.530=320.540=320.(52)20=7520
->điều phải chứng minh.
\(75^{20}=\left(5^2\right)^{20}.3^{20}=5^{40}.3^{20}\); \(45^{10}.5^{30}=\left(3^2\right)^{10}.5^{10}.5^{30}=3^{20}.5^{40}\)
Vậy \(75^{20}=45^{10}.5^{30}\left(=5^{40}.3^{20}\right)\)
Chứng minh:
a) \(\left(2^{10}+2^{11}+2^{12}\right)\)chia hết cho 7
b) \(\left(19^{45}+19^{30}\right)\)chia hết cho 20
a,\(2^{10}+2^{11}+2^{12}=2^{10}.\left(2^2+2+1\right)=2^{10}.7⋮7\)
b, \(19^{45}+19^{30}=19^{30}\left(19^{15}+1\right)\)
Mà \(19^{15}+1⋮\left(19+1\right)\Rightarrow19^{15}+1⋮20\Rightarrow19^{45}+19^{30}⋮20\)
Chú ý: Ý b áp dụng công thức \(a^{2n+1}+b^{2n+1}⋮\left(a+b\right)\)
chứng tỏ rằng
7520 = 4510.530
Ta có :
\(75^{10}.75^{10}=\left(5^{10}.3^{10}.3^{10}\right).\left(5^{10}.5^{10}.5^{10}\right)\)
\(75^{10}.75^{10}=\left(5^{10}.5^{10}.3^{10}\right).\left(5^{10}.5^{10}.3^{10}\right)\)
\(75^{10}.75^{10}=75^{10}.75^{10}\)
Vì vậy : \(75^{20}=45^{10}.5^{30}\)
\(75^{20}=3^{20}.5^{40}\)
\(45^{10}.5^{30}=3^{20}.5^{40}\)
Do đó:\(75^{20}=45^{10}.5^{30}\)(đpcm)