Answer:
The missing coefficient is -8
Step-by-step explanation:
Let
a------> the missing coefficient
we have
[tex]ay^{2}-[-5y-y(-7y-9)]-[-y(15y+4)]=0[/tex]
[tex]ay^{2}-[-5y+7y^{2}+9y]-[-15y^{2}-4y]=0\\ \\ ay^{2}+5y-7y^{2}-9y+15y^{2}+4y=0\\\\ay^{2}-7y^{2}+15y^{2}=0\\\\ay^{2}+8y^{2}=0\\ \\a=-8[/tex]
