Penjelasan dengan langkah-langkah:

11.

(x²-x-6)(2x²-x-15) =

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

(x-2)/(2x+5) =

x = 3 dimasukkan.

(3 -2)/(2(3)+5) =

1/(6+5) =

1/11

12.

(x^(⅓) -3)/(x-27) =

1 ÷ [(x-27)/(x^⅓-3)] =

1 ÷ [x^⅔ + 3x^⅓ + 9] =

nilai x = 27 dimasukkan.

1 ÷ [27^⅔ + 3(27)^⅓ + 9] =

1 ÷ 27 =

1/27

opsiD.

13.

(4-x)/(5-√(x²+9)) =

(4-x)(5+√(x²+9)) / ((5-√(x²+9))(5 + √(x²+9))) =

(-x+4)(5+√(x²+9)) / (25 - (x²+9)) =

(-x+4)(5+√(x²+9)) / (16 - x²) =

(-x+4)(5+√(x²+9)) / (-x+4)(x+4) =

(5+√(x²+9)) / (x+4) =

nilai x = 4 dimasukkan:

(5+√(4²+9)) / (4+4) =

5/4

opsi D

14.

(x-2)/(√(x+7) -3) =

(x-2)(√(x+7) +3) / [ (√(x+7) -3)(√(x+7) +3)] =

(x-2)(√(x+7) +3) / [ x+7 -9] =

(√(x+7) +3)

nilai x = 2 dimasukkan:

(√(2+7) +3) =

3 +3 =

6

opsiA

15.

[a√(x+3) -b]/(x-1) =

[a√(x+3) -b][a√(x+3) +b] /

{(x-1)[a√(x+3) +b]} =

(a²(x+3)-b²) / {(x-1)[a√(x+3) +b]} =

[(a² + (4a²-b²)/(x-1))] / [a√(x+3) +b] =

nilai x =1 dimasukkan:

[(a² + (4a²-b²)/(1-1))] / [a√(1+3) +b] =

(a² + 0)/(2a+b) =

a²/(2a+b)

diketahui hasil limit = 1

a²/(2a+b) = 1

a² = 2a+b

1 = (2a+b)/a²

1 = 1/a + b/a²

a = 1 + b/a

b/a = a -1