(2分支3x+1二次方)-3分支1=9分支1?

[(3x + 1)²/2] - (1/3) = 1/9

兩邊同時乘以 18 :
{[(3x + 1)²/2] - (1/3)} × 18 = (1/9) × 18

9(3x + 1)² - 6 = 2

9(3x + 1)² = 8

(3x + 1)² = 8/9

3x + 1 = √(8/9) 或 3x + 1 = -√(8/9)

3x + 1 = 2(√2)/3 或 3x + 1 = -2(√2)/3

3x = (-3 + 2√2)/3 或 3x = (-3 - 2√2)/3

x = (-3 + 2√2)/9 或 x = (-3 - 2√2)/9