Răspuns :
2 *( x+1 )² - 3 * (x-2) *(x+2) + 5x * (x-3) - ( 3x-1 )²=
2*(x²+2x+1)-3(x²-4)+5x²-15-(9x²-6x+1)=
2x²+4x+2-3x²+12+5x²-15-9x²+6x-1=
-5x²+10x-2=
10x-5x²-2=
5x(2-x)-2
2*(x²+2x+1)-3(x²-4)+5x²-15-(9x²-6x+1)=
2x²+4x+2-3x²+12+5x²-15-9x²+6x-1=
-5x²+10x-2=
10x-5x²-2=
5x(2-x)-2
intai desfacem parantezele:
stim ca
[tex] (a+b)^{2} = a^{2} +2ab+ b^{2} [/tex]
[tex] (x+1)^{2} = x^{2} +2x+1[/tex]
[tex](x-2)(x+2) = x^{2} +2x-2x-4[/tex]
[tex] (3x-1)^{2} = 9 x^{2} -6x+1[/tex]
Inlocuim tinand seama de minusii din fata:
[tex]2x^{2} +4x+2 - 3x^{2} +12 + 5 x^{2} -15x-9 x^{2} +6x-1 =[/tex]
[tex]= -5 x^{2} -5x+14[/tex]
stim ca
[tex] (a+b)^{2} = a^{2} +2ab+ b^{2} [/tex]
[tex] (x+1)^{2} = x^{2} +2x+1[/tex]
[tex](x-2)(x+2) = x^{2} +2x-2x-4[/tex]
[tex] (3x-1)^{2} = 9 x^{2} -6x+1[/tex]
Inlocuim tinand seama de minusii din fata:
[tex]2x^{2} +4x+2 - 3x^{2} +12 + 5 x^{2} -15x-9 x^{2} +6x-1 =[/tex]
[tex]= -5 x^{2} -5x+14[/tex]