Question

A no having two digit the no at tenth place is 4less than the no at once place and there product is 21find the no

Answer 1

Answer:

37

Step-by-step explanation:

Let the number at unit place be x then the number at ten place is x-4.

$x\times (x - 4) = 21$

${x}^{2} - 4x - 21 = 0$

${x}^{2} - 7x + 3x - 21 = 0$

$x(x - 7) + 3(x - 7) = 0$

$(x - 7)(x + 3) = 0$

Therefore, x = 7 or, - 3

But x cannot be negative.

Hence, number is 7.

The required number is 37.