Why does 1212 14641 and 1212 14641 I am not understanding

Why does (-12.1)² = 146.41 and (-12.1²) = -146.41? I am not understanding why the position of the exponent matters.

I need to know how to use this in the quadratic equation. Which do I use for the \"b²-4ac\" part (-12.1²) or (-12.1)².

I really need an explanation to this and not just a simple answer.

We should know that any number : ( -x)^2 = (-x)*(-x) = x^2

because - * - = +

In case quadratic equation : 2x^2 - 3x +2 and compare it with std quadratic equation : ax^2 +bx +c

b^2 -4ac = (-3)^2 -4*2*2 = 9 - 16 = -7

So, (-12.1)^2 = 146.41