simplify (1)

Algebra Level 2

If x = 2017 x=2017 and y = 1 2017 y=\dfrac{1}{2017} then,

( x y + 2 x y + 1 + x y ) ÷ ( x y + 2 x y x y + 1 ) = ? \large \left(\frac{\frac{x}{y}+2}{\frac{x}{y}+1}+\frac{x}{y}\right)\div \left(\frac{x}{y}+2-\frac{\frac{x}{y}}{\frac{x}{y}+1}\right)=?


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3 solutions

X X
May 27, 2018

Let x y = a , a + 2 a + 1 + a a + 2 a a + 1 = a + 2 a + 1 + a a + a + 2 a + 1 = 1 \frac xy=a,\dfrac{\frac{a+2}{a+1}+a}{a+2-\frac{a}{a+1}}=\dfrac{\frac{a+2}{a+1}+a}{a+\frac{a+2}{a+1}}=1

Munem Shahriar
Aug 31, 2018

Assume x = 2017 = a x = 2017 = a and y = 1 2017 = 1 a y = \dfrac 1{2017} = \dfrac 1a . So x y = a 2 \dfrac xy = a^2 .

( x y + 2 x y + 1 + x y ) ÷ ( x y + 2 x y x y + 1 ) = ( a 2 + 2 a 2 + 1 + a 2 ) ÷ ( a 2 + 2 a 2 a 2 + 1 ) = a 2 + 2 + a 2 ( a 2 + 1 ) a 2 + 1 × a 2 + 1 ( a 2 + 1 ) ( a 2 + 2 ) a 2 = a 2 + 2 + a 4 + a 2 a 4 + 2 a 2 + a 2 + 2 a 2 = a 4 + 2 a 2 + 2 a 4 + 2 a 2 + 2 = 1 \begin{aligned} \left(\frac{\frac xy+2}{\frac xy+1}+\frac xy \right)\div \left(\frac xy+2-\frac{\frac xy}{\frac xy+1}\right) & = \left(\dfrac{a^2 + 2}{a^2 +1} + a^2 \right) \div \left(a^2 + 2 - \dfrac{a^2}{a^2 + 1} \right) \\ & = \dfrac{a^2+2 + a^2(a^2 +1)}{a^2 + 1} \times \dfrac{a^2 +1}{(a^2 + 1)(a^2 +2) - a^2} \\ & = \dfrac{a^2 + 2 + a^4 + a^2}{a^4 + 2a^2 + a^2 + 2 - a^2} \\ & = \dfrac{a^4 + 2a^2 + 2}{a^4 + 2a^2 + 2} \\ & = \boxed 1 \\ \end{aligned}

Q = ( x y + 2 x y + 1 + x y ) ÷ ( x y + 2 x y x y + 1 ) Let v = x y = v + 2 v + 1 + v v + 2 v v + 1 Multiply up and down by ( v + 1 ) = v + 2 + v ( v + 1 ) ( v + 2 ) ( v + 1 ) v = v 2 + 2 v + 2 v 2 + 2 v + 2 = 1 \begin{aligned} Q & = \left(\frac{\frac{x}{y}+2}{\frac{x}{y}+1}+\frac{x}{y}\right)\div \left(\frac{x}{y}+2-\frac{\frac{x}{y}}{\frac{x}{y}+1}\right) & \small \color{#3D99F6} \text{Let }v = \frac xy \\ & = \frac {\frac {v+2}{v+1}+v}{v+2-\frac v{v+1}} & \small \color{#3D99F6} \text{Multiply up and down by }(v+1) \\ & = \frac {v+2+v(v+1)}{(v+2)(v+1)-v} \\ & = \frac {v^2+2v+2}{v^2+2v+2} \\ & = \boxed{1} \end{aligned}

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