Aptitude topic. Question on averages

A two-digit number exceeds the sum of its squares by 19 and doubles the product of its digit by 44.find the number

Karthik
29 जून
1858 दृश्य
1 उत्तर

Your Answer

Shruti
29 जून

let xand y be the number represented by 10x+y

10x + y = x^2 + y^2 + 19
10x + y = 2xy + 44
10x + y = 2xy + 44
y - 2xy = 44 - 10x

y(1 - 2x) = 44 - 10x
y = (44 - 10x)/(1 - 2x)
Now, plug:
10x + y = x^2 + y^2 + 19
10x + (44 - 10x)/(1 - 2x) = x^2 + [(44 - 10x)/(1 - 2x)]^2 + 19
Long story short: (7,2) and (3.5,-1.5)
the decimals are excluded because they don't result with two digits
10x + y
10(7) + 2
72