a student solved the inequality x^2 is greater than or equal to 144 by taking the square root of each side to get x is greater than or equal to 12. she wrote the solution set as (negative infinity, 12]. is her solution correct? explain.

Question

anonymous · Answer

This is correct. The question asks for greater than or EQUAL to. The brackets are a symbol of the EQUAL to. - infinity is correct because every number less the 12 includes 11, 10, 9, 8, 7,... etc to infinity. If you use infinity, you must always use parentheses. Therefore (-infinity,  12] is correct