Y ={x+5,x<-1 2x+7,x>-1

The expression you provided appears to be a function defined in two parts. To rewrite it in piecewise form, we can define it as follows:

\( y =\left\{ \begin{array}{ll} x + 5, & \text{ if } x < -1 \\ 2x + 7, & \text{ if } x \geq -1 \end{array} \right. \)

This is a piecewise function that depends on the value of \( x \). It is equal to \( x + 5 \) for values of \( x \) less than -1, and equal to \( 2x + 7 \) for values of \( x \) greater than or equal to -1.