log2{2(x − 1)(x + 2)} < 2 https://www.wolframalpha.com/input?i=log2%7B2%28x+%E2%88%92+1%29%28x+%2B+2%29%7D+%3C+2+&lang=ja
log2{2(x − 1)(x + 2)} < 2
https://www.wolframalpha.com/input?i=log2%7B2%28x+%E2%88%92+1%29%28x+%2B+2%29%7D+%3C+2+&lang=ja