<span />
<span>(2p-q)^2-(q+2p)^2 =
= ((2p)^2 - 2*2p*q + q^2 ) - (q^2 + 2*q*2p + (2p)^2) =
= 4p^2 - 4pq + q^2 - q^2 - 4pq - 4p^2 =
= -8pq
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</span>
4y²=1
y²=1/4
y=1/2 y=-1/2 (2 корня)
x^2-4x-5<0
D=(-4)^2-4*(-5)*1=16+20=36
x1=5
x2=-1
xэ(-1;5)