Works fine for me using an ACER laptop and a cheap LG ultrawide monitor connected via HDMI.
Actually you can use both displays at the same time (enhanced desktop) with a resolution of 4480 x 1080.
This message was posted on behalf of Intel Corporation
The 5th gen processors with HD 5500 support 2560 x 1080 resolution and more with Display Port and HDMI.
More details on the link; pages 38 and 39