\(\left(2x-5\right)^2-4\left(x+3\right)\left(x-3\right)\)
\(=\left(2x-5\right)^2-4\left(x^2-9\right)\)
\(=4x^2-20x+25-4x^2+36\)
\(=-20x+61\)
=.= hok tốt!!
\(\left(2x-5\right)^2-4\left(x-3\right)\left(x+3\right)=4x^2-20x+25-4\left(x^2-9\right)\)
\(=4x^2-20x+25-4x^2+36\)
\(=-20x+61\)
\(\text{(2x−5)}^2\)−4(x+3)(x−3)
=\(\text{(2x−5)}^2\)−4(\(x^2\)−9)
=\(4x^2\)−20x+25−\(4x^2\)+36
= (\(4x^2\)-\(4x^2\))-20+(25+36)
= −20x+61