lim x -> 4 9-x^2 --------- 4- akar x^2 + 7

lim x→4 (9 - x²)/(4 - √(x² + 7))
tidak terdapat = 0/0, substitusilangsung memenuhi
= (9 - 4²)/(4 - √(4² + 7))
= -7/(4 - √23), atau dirasionalkan
= -7(4 + √23)/(16 - 23)
= -7(4 + √23)/-7
= 4 + √23