# Finding the coefficients error by the least squares method

How do I calculate the error $$(\triangle) \space$$of coefficients $$a, b$$ from $$y = a + bx$$ if $$\triangle y = \sqrt{\frac{1}{(n-2)} \sum_{i= 1}^n {(y_i - a - bx_i )^2}}$$

using the least squares method.

I have the answers from my textbook, but I'd still like to understand how they are found $$\triangle a= \triangle y\sqrt{\frac{\sum_{i= 1}^n {x_i^2}}{n\sum_{i= 1}^n{(x_i -\widetilde{x})^2}}{}}$$

$$\triangle b= \triangle y\sqrt{\frac{1}{\sum_{i= 1}^n{(x_i -\widetilde{x})^2}}{}}$$