質問: (4/5)^5.x=(4/5)^7 (3x+1)^3=-26
回答: `(4/5)`$^{5}$ .x = `(4/5)`$^{7}$ ⇒ `x` = `(4/5)`$^{2}$ (3x+1)^3=-27=-3^3 suy ra 3x +1 =-3 x = -3/4