Question

two digit number is such that the product of the digit is 8.When 18 is added to the number,then the digits are reversed.Find the number

Answer 1

let the digit at units place be x and at tens place be y..then original no.=10x+y..now..according to the question=>x*y=8=>x=8/y..now according to the question=>10x+y+18=10y+x=>10x-x+y-10y=-18=>9x-9y=-18=>y-x=18/9=2=>y-8/y=2=>y^2-8=2y=>0=-y^2+2y+8=>0=-y^2+4y-2y+8=>0=y(-y+4)+2(-y+4)=>0=(-y+4)(y+2)=>y=4 and y=-2..so x=8/4=2...so the no. is 10*2+4=>24(ans)

Answer 2

  x + y = 8 

10x + y + 18 = 10y + x 
9x - 9y = -18 
9(x - y) = -18 
x - y = -2 

x + y = 8 
x - y = -2 
2x = 6 
x = 3 
y = 5 

number is 35 

the number is 
10x + y, not xy