ถามคณิตข้อนี้หน่อยย

[Pear2001]

จงหาเซตคำตอบของสมการ

รูทx+7=x-5

Comments

[TheGreatManatee]

substitute sqrt(x) with a

a+7 = a^2 - 5

0 = a^2 - a -12

0 = (a-4)(a+3)

a can be either 4 or -3

however, sqrt(x) >= 0 for all x in Z+

Thus sqrt(x) = 4

x = 16

The set of all solution is {16}