It is known that the function y = f (x) is even on R, and when x ≥ 0, f (x) = x & # 178; - 2x ① Find the analytic expression of F (x) when x ＜ 0. ② draw the diagram of F (x) and write the monotone interval of F (x)

It is known that the function y = f (x) is even on R, and when x ≥ 0, f (x) = x & # 178; - 2x ① Find the analytic expression of F (x) when x ＜ 0. ② draw the diagram of F (x) and write the monotone interval of F (x)

First question: because f (x) is an even function, there is f (x) = f (- x), so when x ≥ 0, f (x) = x & # 178; - 2x when x ≤ 0, f (- x) = (- x) &# 178; - 2 (- x) = x & # 178; + 2x = f (x) second question: the right half of a graph can be drawn by the point drawing method, and then the left side can be drawn symmetrically about the Y axis, the zeros are - 2 and 2, and the monotonic increasing intervals are 0 to positive