Question

dau 100 de puncte pentru toate exercițiile!!​

Answer 1

$\it 7)\ Conform\ T.\ Thales \Rightarrow \dfrac{8}{x+3}=\dfrac{6}{x-0,25}\Rightarrow 8(x-0,25)=6(x+3) \Rightarrow\\ \\ \\ \Rightarrow 8x-2=6x+18 \Rightarrow 8x-6x=18+2 \Rightarrow 2x=20 \Rightarrow x=10$

8) P(X)·Q(X) =(X²-2X-10)(X-5) = X³-2X² -10X - 5X² +10X+50 =X³-7X²+50

P(X)+Q(X) = X²-2X-10+X-5 = X²-X-15

$\it 9)\ f\ admite\ minim \Rightarrow a>0\\ \\ f_{min}=-\dfrac{\Delta}{4a}=0 \Rightarrow \Delta=0 \Rightarrow 9-4a^2=0 \Rightarrow 9=4a^2 \Rightarrow a^2=\dfrac{9}{4}\Rightarrow a=\dfrac{3}{2}$