Mathematics
A two digit number is 4 times the sum of its digits and twice the product of its digits. Find the number.
Quadratic Equations
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Answer
Let the two-digit number be 10x + y.
If the number is 4 times the sum of its digits.
⇒ 10x + y = 4(x + y)
⇒ 10x + y = 4x + 4y
⇒ 10x - 4x = 4y - y
⇒ 6x = 3y
⇒ 2x = y ………. (1)
And, the number is twice the product of its digits.
⇒ 10x + y = 2(xy)
Using equation (1), we get
⇒ 10x + 2x = 2(x 2x)
⇒ 12x = 2(2x2)
⇒ 12x = 4x2
⇒ 12 = 4x
⇒ 3 = x
Putting the value of x in equation (1), we get
y = 2x = 2 3 = 6
The number = 10x + y = 10 3 + 6 = 30 + 6 = 36
Hence, the number = 36.
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