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How to solve this? :)

How to solve this? :)-example-1
User Litek
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1 Answer

15 votes
15 votes

Explanation:

by understanding how a number actually works.

when I write e.g. the number 2648, what did I actually tell you ?

that there is a value or quantity that is

8×10⁰ + 4×10¹ + 6×10² + 2×10³

every number you or anybody else has ever written represented this type of information.

so, now we have a 2-digit number : xy

its value is : y×10⁰ + x×10¹

and because 10⁰ = 1 and 10¹ = 10, this is simply

x×10 + y or 10x + y

the description tells us that

|x - y| = 2

and that xy + yx = 132

that means

10x + y + 10y + x = 132

11x + 11y = 132

we can divide by 11 and get

x + y = 12

like 8+4 or 9+3.

and we know the difference between x and y is 2

like 6 and 4, or 1 and 3.

normally we should know the solution already (I do), but let's finish it formally.

we use one scenario of the absolute value equation :

x - y = 2

x = y + 2

and we use this in the second equation :

y + 2 + y = 12

2y + 2 = 12

2y = 10

y = 5

x = y + 2 = 5 + 2 = 7

the same, just with reversed positions, is the result when using

y - x = 2

so, we get actually 2 solutions that fulfill the requirement : 75 and 57, as they are both also the reverse number to the other.

User Vjeux
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