Salut, am niste exercitii de facut pe care nu le inteleg:
x patrat – 25 supra x patrat + 8x + 15
x² – 25
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x² + 8x + 15
Cum as putea sa rezolv?
Si mai e ceva, cum pot gasii raspunsul pentru radicalii compusi in acest caz:
Radical mare din 13 + 4√3
a)(x^2-25)/(X^2+8x+15)=(x+5)(x-5)/[(X+3)(x+5)]=(x-5)/(X+3)
b)SQRT(13+SQRT(48))=SQRT(A+SQRT(A^2-B^2))->A=13 si A^2-B^2=48->B=9. Deci SQRT(13+SQRT(48))=SQRT((13+9)/2)+SQRT((13-9)/2)=SQRT(11)+SQRT(2)
Radicali compusi :
SQRT(13+4SQRT3)=SQRT(13+SQRT48) = SQRT((13+SQRT(13^2 – 48))/2)+ SQRT((13-SQRT(13^2 – 48))/2) = SQRT(12) + 1
Observa ca 13+4SQRT3 =1+2*SQRT(12) + (SQRT(12))^2 = (1+SQRT12)^2