Question

3*(2, 4х-3) -(6-4, 9х) +2*(0, 7х-5) х=-2

Answer 1

$\displaystyle 3(2,4x-3)-(6-4,9x)+2(0,7x-5)x=-2\\7,2x-9-6+4,9x+1,4x^2-10x=-2\\\\2,1x-15+\frac{7}{5}x^2=-2\\ \\\frac{21}{10}x-15+\frac{7}{5}x^2=-2\\ \\21x-150+14x^2=-20\\ 21x-150+14x^2+20=0\\21x-130+14x^2=0\\14x^2+21x-130=0\\\\x=\frac{-21б\sqrt{21^2-4*14(-130)} }{2*14}=\frac{-21б\sqrt{441+7280} }{28}=\frac{-21б\sqrt{7721} }{28}$