tolong bantuannya,pkai cara ya,please,ditunggu segera!!??

1. a²b + ab² = 6²(3) + 6(3)²
= 36(3) + 6(9) = 108 + 54 = 162 (D)

2. ?

3. (x + 4) (x - 9)
= x² - 9x + 4x - 36
= x² - 5x - 36 (C)

4. 2x² - 9x - 18 = B. (x - 6) (2x + 3)

5. 5/a + 3 + 6/a + 4
= 5(a + 4) + 6(a + 3)/(a + 3) (a + 4)
= 5a + 20 + 6a + 18 / (a² + 7a + 12)
= 11a + 38 / a² + 7a + 12 (D)