問maths 功課題目

2. f = a(m+4/a)
f = am + 4
a = (f-4)/m

3. y = 1/5x-1/x
y = 1/5x - 5/5x
y = (1-5)/5x
5x = (-4)/y
x = -4/(5y)

4. y = 1/2x-1/5x
y = 5/10x - 2/10x
y = (5-2)/10x
x = 3/(10y)

5. y = 2/3x+1/x
y = 2/3x + 3/3x

y = (2+3)/3x
x = 5/(3y)

6. y = 2x/x-2
y(x-2) = 2x
yx - 2y = 2x
-2y = 2x - yx
x = -2y/(2-y) or 2y/(y-2)


7. y = 3x+1/x-1
y(x-1) = 3x + 1
yx - 1 = 3x + 1
(y-3)x = 2
x = 2/(y-3)

8. y = x+2/2-x
y(2-x) = x+2
2y - xy = x + 2
2y - 2 = x+xy
x = 2(y-1)/(1+y)