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Koushik
Koushik asked in Science & MathematicsMathematics · 5 years ago

Math problem. Help needed?

X and Y are integers

X+Y<11. And X>6

What is there smallest possible value of X-Y?

1

2

4

-2

-4

please show working

1 Answer

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  • Dragon.Jade
    Lv 7
    5 years ago

    Hello,

    You should not have modified the problem by changing the ≤≥ symbols to <>.

    In maths, every symbol has a very precise meaning. And doing this actually makes your problem not mathematically solvable.

       X + Y ≤ 11

       -X – Y ≥ -11   ← Multiply by -1, the inequality sign is reversed

       X ≥ 6

       2X ≥ 12   ← Multiply by 2, the inequality sign stays the same

    Then add both inequalities:

       2X + (-X – Y) ≥ 12 + (-11)

       2X – X – Y ≥ 12 – 11

       X – Y ≥ 1

    Thus the minimal value of X–Y should be 1.

    Regards,

    Dragon.Jade :-)

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