Question

Efectuati:
(2x-5)²+3(x-2)(x+2)-(x+4)²

Answer 1

(2x-5)²-3(x-2)(x+2)-(x+4)²
4x²-20x+25+3(x²-4)-(x²+8x+16)
4x²-20x+25+3x²-12-x²-8x-16
6x²-28x-3

Answer 2

4x la 2 - 2x +25 +3(x la 2 -4) - x la 2 - 8x -16=
4x la 2 -2x +25+3x la 2 - 12 -x la 2 - 8x -16=
6x la 2 -7x-3

6x la 2 -7x -3=0

a=6
b=-7
c=-3

▲(delta)=b la 2 - 4ac
=49 -4*6*(-3)
=49+72
=121 → radical din ▲= 11

x1= -b+ radical din▲ supra 2a
=7+11 supra 12
=18 supra 12
=3/2
x2=-b-radical din ▲ supra 2a
=7-11 supra 12
=-4 supra 12
= -1/3