I try to make a color gradient in a triangle but I can't find an efficient way to do that. How do I set gradients from the corners instead from left to right?

I want the base to be from blue to yellow: green.

Thanks in advance!

The best option is probably mesh gradient.

https://www.youtube.com/watch?v=YdqndZ6T3MA

Thanks for the tip, however, that did not work either but I have to admit I find the gradient tool very complex to work with. I am new to Inkscape. Looking further . . . 

Maybe this: