Or get a lower jack, or adjust the ride height to normal.
Jacking on the curved sloping part is risky as it WILL slip sooner or later.
As to raising it up high enough on one jack to get both wheels off the ground, yes you can.
Please remember NEVER to go underneath a jacked up car, You need secondary supports such as a pair of stands or a pile of large wooden blocks (NEVER a stack of bricks!) to make it safe to go under.
A good way of supporting is to place a length of 4 by 2 timber across the car at the front of the floor where it meets the toeboard, where it is stiff. It will normally foul the exhaust so shim it at both sides by two lengths of thick plywood with a gap in the middle. You can then jack the 4 by 2 in the middle, and fit axle stands at both ends, below the sills. Let the jack down slowly until the stands are taking part of the weight and it will be very stable.