✔ 最佳答案
This problem can easily be solved by plugging in the answers provided. You'll quickly find that the answer is (a) -9.
sqrt(73-9) - sqrt(58-9) = sqrt(64) - sqrt(49) = 1
The others don't work.
If you had to solve this algebraically, start by squaring both sides:
(x+73) - 2 sqrt[(x+73)(x+58)] + (x+58) = 1
2x + 130 = 2 sqrt[(x+73)(x+58)]
x+65 = sqrt[(x+73)(x+58)]
Square both sides AGAIN, and
(x+65)^2 = (x+73)(x+58)
x^2 + 130x + 4225 = x^2 + 131x + 4234
x = 4225-4234 = -9