Rozwiąż równanie kwadratowe... zdj. w załączniku.

a) x²-5x-14 = 0 Δ = 25-4·1·(-14) = 25+56 = 81 √Δ = 9 x1 = (5-9)/2 = -2 x2 = (5+9)/2 = 7 b) 2x²-8 = 0 2(x²-4) = 0 2(x-2)(x+2) = 0 x-2 = 0  ∧  x+2 = 0 x = 2     ∧  x = -2 c) x-7x² = 0 x(1-7x) = 0 x = 0  ∧  1-7x = 0                -7x = -1                 x = 1/7 d) (2x+1)²-9(x-1)² = 4-x 4x²+4x+1-9(x²-2x+1) = 4-x 4x²+4x+1-9x²+18x-9= 4-x -5x²+23x-12 = 0 Δ = 529-4·(-5)·(-12) = 529-240 = 289 √Δ = 17 x1 = (-23-17)/(-5)·2 = -40/(-10) = 4 x2 = (-23+17)/(-5)·2 = -6/(-10) = 3/5