At Westonci.ca, we connect you with experts who provide detailed answers to your most pressing questions. Start exploring now! Our platform provides a seamless experience for finding precise answers from a network of experienced professionals. Get immediate and reliable solutions to your questions from a community of experienced professionals on our platform.

A number is such that its ten digit is twice its unit digit. Prove that the number itself must be seven times the sum of its digit

Sagot :

x - ten digit
y - unit digit

[tex]x=2y\\ 10x+y=7(x+y)\\\\ 10\cdot2y+y=7(2y+y)\\ 20y+y=14y+7y\\ 21y=21y \Rightarrow y\in \mathb{R}\Rightarrow x\in \mathb{R}[/tex]

So it's true.
We hope our answers were useful. Return anytime for more information and answers to any other questions you have. Thank you for visiting. Our goal is to provide the most accurate answers for all your informational needs. Come back soon. Westonci.ca is here to provide the answers you seek. Return often for more expert solutions.