Question

Am nevoie urgent de rezolvat aceste ecuatii!!!!
40 de puncte dau
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Answer 1

Bună!

→ f:R->R, f(x)=y; dacă zeroul funcției este 0 ⇒ y=0 ⇒ f(x)=0

f:R->R

∝ a) f(x)=3x-x²

3x-x²=0 ⇒ x(3-x)=0 ⇒

• x=0

   sau

• 3-x=0 ⇒ x=3

∝ b) f(x)=-3x²+x+2

-3x²+x+2=0

a=-3

b=1

c=2

Δ=b²-4ac=1+24=25>0

       ⇒ $x_{1} =\frac{-b-\sqrt{delta} }{2a} =\frac{-1-5}{-6} =\frac{-6}{-6} =1$

       ⇒ $x_{2} =\frac{-b+\sqrt{delta} }{2a} =\frac{-1+5}{-6} =-\frac{4}{6} ^{(2} =-\frac{2}{3}$

∝ c) f(x)=0,(4)x²-1

0,(4)=4/9

$\frac{4x^{2} }{9} -1=0/*9 => 4x^{2} -9=0 => 4x^{2} =9=> x=\sqrt{\frac{9}{4} }$ ⇒ x=±3/2

∝ d) f(x)=4,5x²-2x-1

$\frac{9x^{2} }{2} -2x-1=0$

a=9/2

b=-2

c=-1

Δ=b²-4ac=4+18=22>0

     ⇒ $x_{1}=\frac{-b-\sqrt{delta} }{2a} =\frac{2-\sqrt{22} }{9}$

     ⇒ $x_{2} =\frac{-b+\sqrt{delta} }{2a} =\frac{2+\sqrt{22} }{9}$