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Two positive real numbers have a sum of 5 and product of 5. Find the number.?

Two positive real numbers have a sum of 5 and product of 5. Find the number.

7 Answers

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  • Anonymous
    1 decade ago
    Favourite answer

    Let

    X = first number

    Y = second number

    X + Y = 5 -- Equation 1

    XY = 5 -- Equation 2

    From Equation 2, since Y = 5/X and substituting this into Equation 1,

    X + 5/X = 5

    Simplifying the above,

    X^2 + 5 = 5X

    X^2 - 5X + 5 = 0

    Solving for the roots of the above using the quadratic formula,

    X = [5 ± sqrt(5)]/2

    and solving for Y,

    Y = 5/X = 5/[5 ± sqrt(5)]/2

    Y = 10/[5 ± sqrt(5)]

    Hope this helps.

  • Anonymous
    1 decade ago

    Find two equations. To do this, asssign a random variable to your unknowns.

    So two numbers sums equal 5? Then x+x=5 or 2x=5

    Their products? y*y=5 or y^2=5

    Solve for the equation and you will see the answer is 2 and 1/2

  • 1 decade ago

    the two numbers are 2.5 + sqrt(5) / 2 and 2.5 - sqrt(5) / 2

    two equations:

    x + y = 5

    xy = 5

    rearranging the first equation:

    y = 5 - x

    sub into second equation

    x(5 - x) = 5

    5x - x^2 = 5

    x^2 - 5x + 5 = 0

    using the quadratic formula with a = 1, b = -5, and c = 5:

    x = [5 +/- sqrt(5^2 - 4(5))] / 2

    x = [5 +/- sqrt(5)] / 2, yielding the two positive numbers:

    2.5 + sqrt(5) / 2 and 2.5 - sqrt(5) / 2

    check: sum = 5 yep

    (2.5 + sqrt(5)/2)(2.5 - sqrt(5) / 2) =

    2.5^2 - 5/4 = 6.25 - 1.25 = 5 yep

  • 1 decade ago

    Since the numbers in question add up to 5, call them x and 5-x. Then make their product equal to 5:

    x(5-x) = 5

    Multiply it out and solve:

    5x-x² = 5

    x²-5x+5 = 0

    x = (5±√(25-20)) / 2

    x = 2.5±(√5)/2

    Therefore, the numbers are approximately 1.4 and 3.6.

  • 1 decade ago

    Let the numbers be x and y.

    x + y = 5

    x*y = 5

    Take the first equation:

    x + y = 5

    Subtract x from both sides:

    y = 5 - x

    Plug into other equation:

    x(5 - x) = 5

    Distribute x:

    5x - x² = 5

    Add x² and subtract 5x from both sides:

    x² - 5x + 5 = 0

    Apply the quadratic formula to solve for x:

    x = [5 ± √((-5)² - 4(1)(5))]/((2)(1))

    x = [5 ± √(25 - 20)]/2

    x = [5 ± √(5)]/2

    Find y:

    y = 5 - x

    y = 5 - [5 ± √(5)]/2

    y = 10/2 - [5 ± √(5)]/2

    y = [5 ± √(5)]/2

    So x=y=[5 ± √(5)]/2

  • ?
    Lv 6
    1 decade ago

    xy = 5....1

    x+y = 5...2

    x = 5/y

    5/y + y = 5

    5 + y^2 = 5y

    y^2 -5y + 5 = 0

    y1= 3.618

    y2 = 1.381966

    put y1 and y2 into 1

  • 1 decade ago

    This is Impossible there is no solution.

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