a two digit number is 4 times the sum of its digit and twice the product of the digit find the number
Answers
6+3=9 and 9×4=36.
3×6=18 and 18×2=36.
SOLUTION :
Let the digit at the tens and units place be x and y .
Two digit number = 10x + y
A T.Q
Number = 4(sum of the digits) & Number = 2(product of the digits)
10x + y = 4(x + y) And 10x + y = 2xy …………(1)
10x + y = 4x + 4y
10x - 4x = 4y - y
6x - 3y = 0
3(2x - y) = 0
2x - y = 0
2x = y ……………….(2)
Put this value of y in eq 1
10x + y = 2xy
10x + 2x = 2x(2x)
12x = 4x²
4x² - 12x = 0
4x(x - 3) = 0
4x = 0 or (x - 3) = 0
x = 0 or x = 3
Since, the given number is a two digit number so its tens digit cannot be zero ( x ≠ 0 )
Therefore , x = 3
Put this value of x in eq 2,
y = 2x
y = 2 (3)
y = 6
Required number = 10x + y
= 10(3) + 6
= 30 + 6
Required number = 36
Hence, the Required two digit number is 36 .
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