Respuesta :
To prove the divisibility lets expand each number first to get the complete picture of the problem
51^7 = 8.974106779 . 10^11
51^6 = 1.75962878 . 10^10
(51^7 - 51^6) = 8.974106779 . 10^11 - 1.75962878 . 10^10
= 8.798143901. 10^11
[tex]\frac{8.798143901. 10^11}{25}[/tex]
= 3.51925756. 10^10
That is the answer expressed in scientific notation
= 35192575600
Which means the divisibility is proven
Step-by-step explanation:
[tex]51^7-51^6=51^{6+1}-51^6\\\\\text{use}\ a^n\cdot a^m=a^{n+m}\\\\=51^6\cdot51^1-51^6\cdot1\\\\\text{use the distributive property}\ a(b-c)=ab-ac\\\\=51^6\cdot(51-1)=51^6\cdot50=51^6\cdot(2\cdot25)=25\cdot(51^6\cdot2)[/tex]
[tex]\text{One of the factors of the product is the number 25.}\\\\\bold{CONCLUSION:}\\\\\text{The whole product is divisible by 25.}[/tex]
[tex]\text{Therefore}\ 51^7-51^6\ \text{is divisible by 25.}[/tex]