Optimize Of Quadratic Polynomial

Why we take Square of Error Instead of Modulus Operation in Optimization Problems??

Having a square as opposed to the absolute value function gives a nice continuous and differentiable function (absolute value is not differentiable at 0) - which makes it the natural choice, especially in the context of estimation and regression analysis.
Because we have to minimize the error and finding minima of a differentiable functions is pretty straightforward

Also, by squaring, large differences are emphasized.(Think of the effect outliers would have). Apart from amplifying large differences, squaring also minimizes tiny differences.

Modulus function is also continuous and differentiable .
(Square value non differentiable at tangent or mima).

Finding mima will be easy in squared function agree.YES

As E = |y-h(x)| find min value of h(x) may be difficult.
h(x) = mx+c