Question

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2n^2-5,5n-10
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Answer 1

$2n^2-5,5n-10=0\, |\cdot 2\\\\4n^2-11n-20=0\\\\D=441\; ,\; \; n_1=\frac{11-21}{8}=-\frac{10}{8}=-1,25\\\\n_2=\frac{11+21}{8}=\frac{32}{8}=4\\\\2n^2-5,5n-10=2\cdot (n+1,25)\cdot (n-4)=(2n+2,5)\cdot (n-4)$

$P.S.\; \; \; \; 2n^2-5,5n-10=\\\\=2n^2-\frac{11}{2}n-10=2\cdot \Big (n^2-\frac{11}{4}n-5\Big )=2\cdot \Big ((n-\frac{11}{8})^2-(\frac{11}{8})^2-5\Big )=\\\\=2\cdot \Big ((n-\frac{11}{8})^2-\frac{121}{64}-5\Big )=2\cdot \Big ((n-\frac{11}{8})^2-\frac{441}{64}\Big )=[\; \frac{441}{64}=(\frac{21}{8})^2\; ]=\\\\=2\Big ((n-\frac{11}{8})-\frac{21}{8}\Big )\cdot \Big ((n-\frac{11}{8})+\frac{21}{8}\Big )=\\\\= 2(n-\frac{32}{8})(n+\frac{10}{8})=2(n-4)(n+1,25)$

$P.P.S.\; \; \; x^2\pm px+q=(x\pm \frac{p}{2})^2-(\frac{p}{2})^2+q$