Question

-3x^2+6x-7>0 ??????????????????????

Answer 1

-3x la puterea a doua=-3x×(-3x)=9x²
deci 9x²+6x-7>0 
Δ=b²-4ac
Δ=6²-4×9×(-7)=36-36×(-7)=36+252=288
x₁=-b-√Δ/2a=-6-√288/2×9=-6-12√/2 /18=-6(1-2√2)/18 (6 cu 18 se simplifica)=-1(1-2√2)/3=-1+2√2 totul supra 3
X₂=-b+√Δ/2a=-6+√288/2×9=-6+12√2totul supra 18=-6(-1-2√2)totul supra 18 (6 cu 18 se simplifica)=-1(1-2√2) totul supra 3=-1+2√2 totul supra 3

aia care mi-ai cerut-o
9(3x+4)>3(5x-1)
9×3x+9×4>3×5x-3×1
27x-36>15x-3
27x-15x>-3+36
12x>33=> x>33/12 se simplifica cu 3=>x>11/4 deci xapartine (11/4, plus infinit )