[tex] \frac{(2x+1)(x+3)}{(2x-1)(2x+1)} = \frac{2 x^{2} +7x+3}{4 x^{2}+2x-2x-1 } = \frac{2x^{2}+7x+3 }{4 x^{2}-1 } [/tex]
[tex] \frac{(x+7y)(x-7y)}{(x-7y)(x+7y)} = \frac{ x^{2}+7xy-7xy-49 y^{2} }{ x^{2} +7xy-7xy-49 y^{2} } = \frac{ x^{2}+49 y^{2} }{ x^{2}+49 y^{2} } =1[/tex]
