2(x-3.5) = 10 ==> x - 3.5 = 5 ==> x = 5 +3.5 ==> x = 8.5 检验 左边= 2 * (8.5 - 3.5 ) = 2 * 5 = 10 右边= 10 左边= 右边 所以x = 8.5 是原方程的解.