Question

设函数f（x）=|2x+1|-|x-3| 解不等式f（x）＞0 已知关于x的不等式a+3

Answer 1

f(x) = |2x + 1 |- |x - 4| > 0

|2x + 1| > |x - 4|

|2x + 1|² > |x - 4|²

x² + 4x - 5 > 0

x > 1 或 x < - 5

f(x) + 3|x - 4| > m

|2x + 1| + 2|x - 4| > m

x < -1/2 |2x + 1| + 2|x - 4| = -4x + 7 > 9

-1/2 ≤ x ≤ 4 |2x + 1| + 2|x - 4| = 9

x > 4 |2x + 1| + 2|x - 4| = 4x - 7 > 9

m < 9