The difference of two numbers is 4 and the product is 140 find the number and form quadratic equation

Mathematics

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Step-by-step solution

5 steps
  1. Define the numbers and set up the equations.

    Let the two numbers be xx and yy.
    The difference of the two numbers is 4:

    x−y=4(1)x - y = 4 \quad (1)

    The product of the two numbers is 140:

    x⋅y=140(2)x \cdot y = 140 \quad (2)
  2. Form a quadratic equation.

    From equation (1), express xx in terms of yy:

    x=y+4x = y + 4

    Substitute this expression for xx into equation (2):

    (y+4)y=140(y+4)y = 140

    Expand the equation:

    y2+4y=140y^2 + 4y = 140

    Rearrange the equation into the standard quadratic form ay2+by+c=0ay^2 + by + c = 0:

    y2+4y−140=0y^2 + 4y - 140 = 0

    The quadratic equation is y2+4y−140=0\boxed{y^2 + 4y - 140 = 0}.

  3. Solve the quadratic equation for yy.

    We can solve y2+4y−140=0y^2 + 4y - 140 = 0 using the quadratic formula y=−b±b2−4ac2ay = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}.
    Here, a=1a=1, b=4b=4, c=−140c=-140.

    y=−4±42−4(1)(−140)2(1)y = \frac{-4 \pm \sqrt{4^2 - 4(1)(-140)}}{2(1)} y=−4±16+5602y = \frac{-4 \pm \sqrt{16 + 560}}{2} y=−4±5762y = \frac{-4 \pm \sqrt{576}}{2} y=−4±242y = \frac{-4 \pm 24}{2}

    This gives two possible values for yy:

    y1=−4+242=202=10y_1 = \frac{-4 + 24}{2} = \frac{20}{2} = 10 y2=−4−242=−282=−14y_2 = \frac{-4 - 24}{2} = \frac{-28}{2} = -14
  4. Find the corresponding values for xx.

    Using x=y+4x = y + 4:
    If y=10y = 10:

    x=10+4=14x = 10 + 4 = 14

    If y=−14y = -14:

    x=−14+4=−10x = -14 + 4 = -10
  5. State the numbers.

    The two numbers are either 14 and 10\boxed{14 \text{ and } 10} or −10 and −14\boxed{-10 \text{ and } -14}.

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