伐數分式及公式3(請盡快回答)

1.
(a)
(1 / x) + (2 / x)
= (1 + 2) / x
= 3 / x

(b)
(3 / a) + (5 / a)
= (3 + 5 ) / a
= 8 / a

(c)
(2y / a) + (5y / a)
= (2y + 5y) / a
= 7y / a

(d)
(1 / 5x) + (4 / 5x)
= (1 + 4) / 5x
= 5 / 5x
= 1 / x

(e)
(a / 2b) + (3a / 2b)
= (a + 3a ) / 2b
= 4a / 2b
= 2a / b

(f)
(a / 2b) + (3a / 2b)
= (a + 3a ) / 2b
= 4a / 2b
= 2a / b

(g)
(6y/b) + (10y/b)
= (6y + 10y) / b
= 16y / b

(h)
(2 / b) + (3 / 3b)
= (2 / b) + (1 / b)
= (2 + 1) / b
= 3 / b

(i)
(1 / 2x) + (2 / 3x)
= (3 / 6x) + (4 / 6x)
= (3 + 4) / 6x
= 7 / 6x

(j)
(5 / 6c) + (7 / 8c)
= (20 / 24c) + (21 / 24c)
= (20 + 21) / 24c
= 41 / 24c


====
(h)
(3 / 2a) - (7 / 2a)
= (3 - 7) / 2a
= -4 / 2a
= -2 / a

(i)
(3 / 4ab) - (2 / 4ab)
= (3 - 2) / 4ab
= 1 / 4ab

(j)
(3 / 5c) - (2 / 3c)
= (9 / 15c) - (10 / 15c)
= (9 - 10) / 5c
= -1 / 5c


====
2.
(a)
(5 / x) - (2 / x)
= (5 - 2) / x
= 3 / x

(b)
(12 / a) - (9 / a)
= (12 - 9) / a
= 3 / a

(c)
(8a / c) - (7a / c)
= (8a - 7a) / c
= a / c

(d)
(15 / 6a) - (3 / 6a)
= (15 - 3) / 6a
= 12 / 6a
= 2 / a

(e)
(7b / 2k) - (5b / 2k)
= (7b - 5b) / 2k
= 2b / 2k
= b / k

(f)
(10s / 4a) - (4s / 4a)
= (10s - 4s) / 4a
= 6s / 4a
= 3s / 2a

(g)
(2 / 3x) - (1 / 4x)
= (8 / 12x) - (3 / 12x)
= (8 - 3) / 12x
= 5 / 12x

(h)
(3 / 2a) - (7 / 2a)
= (3 - 7) / 2a
= -4 / 2a
= -2 / a

(i)
(3 / 4ab) - (2 / 4ab)
= (3 - 2) / 4ab
= 1 / 4ab