✔ 最佳答案
Q1)
1 / (x - 1) - 1 / (x + 1)
= (x + 1) / (x + 1)(x - 1) - (x - 1) / (x + 1)(x - 1)
= [(x + 1) - (x - 1)] / (x + 1)(x - 1)
= (x + 1 - x + 1) / (x + 1)(x - 1)
= 2 / (x + 1)(x - 1)
Q2)
2 / (x + 1) - 1 / (x - 1)
= 2(x - 1) / (x + 1)(x - 1) - (x + 1) / (x + 1)(x - 1)
= [2(x - 1) - (x + 1)] / (x + 1)(x - 1)
= (2x - 2 - x - 1) / (x + 1)(x - 1)
= (x - 3) / (x + 1)(x - 1)
Q3)
(m - n) / (m + n) + (m + n) / (m - n)
= (m - n)2 / (m + n)(m - n) + (m + n)2 / (m + n)(m - n)
= [(m - n)2 + (m + n)2]2 / (m + n)(m - n)
= (m2 - 2mn + n2 + m2 + 2mn + n2) / (m + n)(m - n)
= (2m2 + 2n2) / (m + n)(m - n)
= 2(m2 + n2) / (m + n)(m - n)
Q4)
y = √(x3 - z)
y2 = [√(x3 - z)]2
x3 - z = y2
x3 = y2 + z
x = (y2 + z)1/3
Q5)
T = 2π√(1/g)
T2 = [2π√(1/g)]2
4π2(1/g) = T2
(1/g) = T2/4π2
g = 4π2/T2
Q6)
3a = 2 + 5 / (2 - b)
5 / (2 - b) = 3a - 2
(2 - b) / 5 = 1 / (3a - 2)
2 - b = 5/ (3a - 2)
- b = - 2 + 5 / (3a - 2)
b = 2 - [5 / (3a - 2)]
Q7)
A(1 + r%)2 = s
(1 + r%)2 = s/A
1 + r% = √(s/A)
r% = -1 + √(s/A)
r = 100[-1 + √(s/A)]
Q8)
d = i / (1 + i)
d(1 + i) = i
d + di = i
i - di = d
i(1 - d) = d
i = d / (1 - d)
Q9)
(az + b) / (cz + d) = w
az + b = w(cz + d)
az + b = wcz + wd
az - wcz = wd - b
(a - wc)z = wd - b
z = (wd - b) / (a - wc)
Q10)
a)
A = 2πr(h + r)
2πr(h + r) = A
h + r = A/2πr
h = -r + (A/2πr)
b)
h = -(7) + {[1408/2(7)] x (7/22)}
h = 25
