Question

calculati formulele de calcul prescurtat
a). (1+x)la a doua+(2+x)la a doua-(3+x)la a doua
b). (2x+3y)la a doua+4x(3x-2)+(2x-1)la a doua
c). (2x+3y)la a doua+(2x+3y)(2x-3y)

Answer 1

a) (1+x)²+(2+x)²-(3+x)²=(1+2x+x²)+(4+4x+x²)-(9+6x+x²)=1+2x+x²+4+4x+x²-9-6x-x²=x²-4=(x-2)(x+2)

b) (2x+3y)²+4x(3x-2)+(2x-1)²=4x²+12xy+9y²+12x²-8x+4x²-4x+1=20x²+9y²+12xy-12x+1

c) (2x+3y)²+(2x+3y)(2x-3y)=4x²+12xy+9y²+4x²-6xy+6xy-9y²=8x²+12xy=4x(2x+3y)