Question

решите уравнение 2x²+5x-3/2x²-x=0
2) упростить выражение (8-2√15)(√5+√3)²

Answer 1

$\frac{2x^{2}+5x-3 }{2x^{2}-x }=0\\\\\left \{ {{2x^{2} +5x-3=0} \atop {2x^{2}-x\neq0}} \right.\\\\2x^{2}+5x-3=0\\\\D=5^{2}-4*2*(-3)=25+24=49=7^{2}\\\\x_{1}=\frac{-5-7}{4}=-3\\\\x_{2}=\frac{-5+7}{4} =0,5\\\\2x^{2}-x\neq0\\\\x(2x-1)\neq0\\\\x\neq0\\\\2x-1\neq0\\\\x\neq0,5\\\\OTVET:-3$

$2)(8-2\sqrt{15})(\sqrt{5}+\sqrt{3})^{2} =(8-2\sqrt{15})(5+2\sqrt{15}+3)=(8-2\sqrt{15})(8+2\sqrt{15})=8^{2}-(2\sqrt{15})^{2}=64-60=4$