C# - float[][] declaration

Question

I'm trying to declare this kind of variable:

float[][]

Things that didn't work for me (wouldn't compile) -

float[][] inputs = new float[10][5];
float[][] inputs = new float[10, 5];

When trying to declare the array like this -

int a = 3;
int b = 2;

float[][] inputs = new float[][]
{
   new float[a],
   new float[b]
};

I get a multidimensional array with two float arrays instead of an array that has 3 arrays and every array size is 2.