Hi I got this wrong and I need help and need someone to teach me how to get it right thank u

Answer:
[tex]4y^2+14y+34[/tex]Explanation:
Here, we want to simplify the polynomial and put in standard form
We start by expanding the middle term as follows:
[tex]\begin{gathered} 3y^2+(y+7)^2\text{ - 15} \\ 3y^2+y^2\text{ + 14y+49-15} \\ 4y^2+14y+34 \end{gathered}[/tex]Writing in standard form simply means arranging from the highest power (exponent) to the lowest