Simplify. \[ \left(-4 y^{2}+6 y\right)+\left(-5 y^{2}-7 y+1\right) \]

Step 1 ：The given expression is \(-4 y^{2}+6 y -5 y^{2}-7 y+1\).

Step 2 ：To simplify the expression, we need to combine like terms. Like terms are terms that have the same variables and powers.

Step 3 ：The like terms in the expression are \(-4y^2\) and \(-5y^2\), and \(6y\) and \(-7y\).

Step 4 ：Combining the like terms, we get \(-9y^2 - y + 1\).

Step 5 ：So, the simplified expression is \(\boxed{-9y^2 - y + 1}\).