Square of 4X = 12X: 4X= 12 X=3.
10×3+2×3=36 A: This two-digit number is 36.
Another is: suppose the decimal digit is 10(X-3) and the unit digit is X. 。
Solution: x squared = 10 (x-3)+x squared = 10x-30+x squared-1x+30 = 0.
Cross multiplication solution: (X-5), (X-6)=0.
X 1=5 X2=6 Both are roots.
10×(5-3)+5= 25 10×(6-3)+6=36。
2. Suppose that this number is X. Solution: X+(X 1/2) square =8 X+X 1/4 square =8.
X 1/4 square +X-8=0 Two sides multiplied by 4: x square +4X-32=0.
The solution of cross multiplication: (X+8)(X-4) =0 X 1=-8 is irrelevant.
X2=4
This number is 4.