Four Basic Operations In A System Of Equations

Algebra Level 4

{ x 1 + x 2 + x 3 + x 4 = 2015 x 1 x 2 x 3 x 4 = 2 × 2015 x 1 × x 2 × x 3 × x 4 = 3 × 2015 x 1 ÷ x 2 ÷ x 3 ÷ x 4 = 4 × 2015 \large {\begin{cases} { x }_{ 1 }+{ x }_{ 2 }+{ x }_{ 3 }+{ x }_{ 4 }=2015\\ { x }_{ 1 }-{ x }_{ 2 }-{ x }_{ 3 }-{ x }_{ 4 }=2\times 2015\\ { x }_{ 1 } \times { x }_{ 2 } \times { x }_{ 3 } \times { x }_{ 4 }=3\times 2015\\ { x }_{ 1 } \div { x }_{ 2 } \div { x }_{ 3 } \div { x }_{ 4 }=4\times 2015 \end{cases}}

Find the number of ordered quadruples ( x 1 , x 2 , x 3 , x 4 ) ({ x }_{ 1 },{ x }_{ 2 },{ x }_{ 3 },{ x }_{ 4 }) of real numbers which satisfy the system of equations above.


The answer is 0.

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1 solution

Otto Bretscher
Nov 15, 2015

Very nice and surprisingly quick!

Adding the first two equations gives 2 x 1 = 3 2015 2x_1=3*2015 , and multiplying the last two gives x 1 2 = 12 201 5 2 x_1^2=12*2015^2 ... incompatible!

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