Oblicz równania. a) 2x(x-3)+3(x-4)+4(x-5)=0 b) 8x+5=2(4x+2,5) c) 1-0,2x=-0,3x d) 1- [latex]frac{6}{7} [/latex] x=[latex]frac{4}{7} [/latex] Pilnie potrzebne !

a) 2x(x - 3) + 3(x + 4) + 4(x - 5) = 0 2x² - 6x + 3x + 12 + 4x - 20 = 0 2x² + x - 8 = 0 Δ = 1² - 4 · 2 · (- 8) = 65 √Δ = √65 x1 = (- 1 - √65) / (2 · 2) = (- 1 - √65) / 4 x2 = (- 1 + √65) / (2 · 2) = (- 1 + √65) / 4 b) 8x + 5 = 2(4x + 2,5) 8x + 5 = 8x + 5 0 = 0 c) 1 - 0,2x = - 0,3x 0,1x = - 1 / : 0,1 x = - 10 d) 1 - [latex] frac{6}{7} [/latex]x = [latex] frac{4}{7} [/latex] - [latex] frac{6}{7} [/latex]x = - [latex] frac{3}{7} [/latex] / : (- [latex] frac{6}{7} [/latex]) x = [latex] frac{1}{2} [/latex]