Question

$(-5-2y)²$(-5-2y)²

Answer 1

(-5)²-2.(-5)(-2y)+(-2y)²
25-20y+4y²
4y²-20y+25
a=4    b=-20   c=25
Δ=b²-4ac
Δ=(-20)²-4.4.25
Δ=400-400
Δ=0
x=(-b+-√Δ) / 2a
x'=x"=$\frac{-(-20)}{2.4}$
x'=x"=$\frac{20}{8} = \frac{5}{2}$=2,5