tolong yang jago matematika nomer 15 sampai 18

Persamaan Bentuk Pecahan
..
(di lampiran)

15)
[1/(x^2 + 4x + 3)] + [1/(x + 3)]
= [1/(x + 3)(x + 1)] + [(x + 1)/(x + 3)(x + 1)]
= [1 + x + 1]/(x + 3)(x + 1)
= (x + 2)/(x + 3)(x + 1)
= (x + 2)/(x^2 + 4x + 3)

16)
[1/(a^2 + 2a + 1)] + [1/(a + 1)]
= [1/(a + 1)(a + 1)] + [(a + 1)/(a + 1)(a + 1)]
= (1 + a + 1)/(a + 1)(a + 1)
= (a + 2)/(a + 1)(a + 1)
= (a + 2)/(a + 1)^2
= (a + 2)/(a^2 + 2a + 1)

17)
[1/(a^2 + 2a + 1)] + [1/(a^2 - 1)]
= [1/(a + 1)(a + 1)] + [1/(a - 1)(a + 1)]
= [(a - 1)/(a - 1)(a + 1)(a + 1)] + [(a + 1)/(a - 1)(a + 1)(a + 1)]
= [a - 1 + a + 1]/[(a - 1)(a + 1)(a + 1)]
= (2a)/(a - 1)(a + 1)(a + 1)
= (2a)/(a - 1)(a + 1)^2
= (2a)/(a^3 + a^2 - a - 1)

18)
[(x + 4)/(x^2 - 9)] - [1/(x - 3)]
= [(x + 4)/(x - 3)(x + 3)] - [(x + 3)/(x - 3)(x + 3)]
= [x + 4 - (x + 3)]/(x - 3)(x + 3)
= (x + 4 - x - 3)/(x - 3)(x + 3)
= 1/(x - 3)(x + 3)
= 1/(x^2 - 9)