7. A two digit number is such that the product of
digits is 12. When 36 is added to this number, ti
digits interchange their places. Find the number,
Answers
Answer:
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Step-by-step explanation:
Let the ten's digit be x and unit's digit be y.
Number = 10x + y
xy = 12 ⇒ y = 12/x … (i)
Also, 10x+y+36 = 10y+x
9x-9y+36 = 0
x-y+4 = 0 … (ii)
From (i) and (ii),
x+4 = 12/x
x^2+4x-12=0
(x+6)(x-2) =0
x=2 or x=-6
Rejecting x = -6, we have x = 2.
y=12/x =12/2=6
Thus, the required number is 2 x 10 + 6 = 26.
Step-by-step explanation:
Let a digit at unit’s place be x and at ten’s place by y .
Then according to problem
Required no. = 10y + x
On interchanging the digits
Number formed = 10x + y
xy = 12
∴ x = 12/y
10y + x + 36 = 10x + y
10y + x – 10x – y = - 36
9y – 9x = - 36
9(y – x) = - 36
y – x = - 36/9
y – x = - 4
On substituting value of x = 12/y
y - 12/y = - 4
y2 – 12/y = - 4
y2 + 4y – 12 = 0
y2 + 6y – 2y – 12 = 0
y(y + 6) – 2(y + 6) = 0
( y + 6)(y – 2) = 0
y = - 6, 2
When y = 2
x = 12/2 = 6
Required no. = 10y + x
= 10 × 2 + 6
= 20 + 6
= 26