যদি log(a + 3) + log(a - 3) = 1 হয়, তাহলে a = কত?

প্রশ্ন: যদি log(a + 3) + log(a - 3) = 1 হয়, তাহলে a = কত?সমাধান:log(a + 3) + log(a - 3) = 1⇒ log{(a + 3)(a - 3)} = 1⇒ log(a2 - 32) = 1⇒ log(a2 - 9) = log10⇒ a2 - 9 = 10⇒ a2 = 19∴ a = √19