Question

For what value of p,-4 is a zero of the polynomial x square-2x-(2p+3)

Answer 1

we have that
x²-2x-(2p+3)

if -4 is a zero of the polynomial
so
for x=-4
x²-2x-(2p+3)=0----> (-4)²-2*(-4)-(2p+3)=0-----> 16+8-2p-3=0
21-2p=0
2p=21
p=21/2-----> p=10.5