Question

x^2+10x+25/x^2-9 : 4x+20/2x+6
При х=-7

Answer 1

$\frac{x^{2}+10x+25 }{x^{2}-9} :\frac{4x+20}{2x+6} =\frac{x^{2}+10x+25 }{x^{2}-9} *\frac{2x+6}{4x+20} =\frac{(x+5)^{2} }{(x-3)(x+3)} *\frac{2(x+3)}{4(x+5)} =\frac{x+5}{x-3} *\frac{2}{4} =\frac{x+5}{x-3} *\frac{1}{2} =\frac{x+5}{2x-6};x=7\\\\\\\frac{7+5}{2*7-6} =\frac{12}{8} =1.5$