Question

[minecraftjaki]

Find all natural numbers having two digit , knowing that twice the units digit 1 more than the ten digit , and if we write that two digits in reverse order, we get a new number which is 27 less than the old one

Answer 1

[Luân Đào]

Tell the numbers to find are \(\overline{ab}\)

\(\Rightarrow\left\{{}\begin{matrix}2b-a=1\\\overline{ab}-\overline{ba}=27\end{matrix}\right.\)

=> 10a + b - 10b - a = 27

=> 9a - 9b = 27

=> a-b = 3

=> a = b + 3

=> 2b - 1 = b+3

=> 2b - b = 3 + 1

=> b = 4

=> a = \(2\cdot4-1=7\)

So he number to find is 74

Answer 2

[minecraftjaki]

Giup mik nhe Luân Đào