can someone help me with interval A = x belongs to R and B = (x belongs to R; square root of x^2 = -x) ............ what are the numbers that belong to B please thanks

If I read this correctly, the numbers that belong to B are reals and satisfy √ [x^2 ] = - x

Note that √[x^2] is defined as l x l

So.......

l x l = - x when x = (- infinity, 0 ]

Ok thanks and can you please tell my why, sorry that I posted another question but I wanted to clarify it more.

Notice that

l 0 l = - 0 = 0

Now....suppose that x is negative

So

l x l = - x

For instance ..... suppose that x = - 3 .....we have......

l -3 l = - (-3) = 3