Lots of points! will give brainiest. (no spam plz) how would i answer these?

Explain why the function is discontinuous at the given number a. (select all that apply.) f(x) = 1 x + 1 a = −1 f(−1) is undefined. lim x→−1+ f(x) and lim x→−1− f(x) exist, but are not equal. lim x→−1 f(x) does not exist. f(−1) and lim x→−1 f(x) exist, but are not equal. none of the above

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

How do you write y-10=2 (x-8) in standard form