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Tough maths question- Can anybody answer this? watch

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    (Original post by Mathsgu)
    The question is:

    Change one value in the equation so that there is one solution

    2xsquared + 7x + 3 =0

    Give as many possible solutions as you can.
    You mean find x or change either 2,7,3?
    If it's x then the answers are -3 & -1/2

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    2 change to 49/12 or
    7 change to +- root 24 or
    3 change to 49/8
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    (Original post by Mathsgu)
    The question is:

    Change one value in the equation so that there is one solution

    2xsquared + 7x + 3 =0

    Give as many possible solutions as you can.
    Do you know how to check whether a quadratic equation has a repeated root and so one one solution?
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    Basically change any value within the equation, either the x or the 7 or the 3 values. And by changing this equation will only give one x value when solved, no the two solutions that this equation has at the moment.

    Hopefully that will make sense. Here's a picture of the question if that helps.
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    (Original post by ian.slater)
    Do you know how to check whether a quadratic equation has a repeated root and so one one solution?
    No I'm not sure on how to do that although I can vaguely remember covering it
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    (Original post by Mathsgu)
    No I'm not sure on how to do that although I can vaguely remember covering it
    The solutions to the equation ax^2 + bx + c = 0 are given by the well-known formula:

    x = (-b+/-sqrt(b^2-4ac)/2a

    so you normally get two solutions. But if the bit in the sqrt is zero, you only get one.

    That bit, b^2 - 4ac , is called the discriminant.

    So what do you have to change the coefficients to, in order to make the discriminant zero? You can change one of a, b or c at a time.
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    (Original post by Kim-Jong-Illest)
    2 change to 49/12 or
    7 change to +- root 24 or
    3 change to 49/8
    Thank you! Could I ask how you got to those answers?
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    (Original post by ian.slater)
    The solutions to the equation ax^2 + bx + c = 0 are given by the well-known formula:

    x = (-b+/-sqrt(b^2-4ac)/2a

    so you normally get two solutions. But if the bit in the sqrt is zero, you only get one.

    That bit, b^2 - 4ac , is called the discriminant.

    So what do you have to change the coefficients to, in order to make the discriminant zero? You can change one of a, b or c at a time.
    Exactly
    One "delta" (how I call that formula) that gives zero is 4^2-4.1.4 so b=4 a=1 c=4

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    (Original post by ian.slater)
    The solutions to the equation ax^2 + bx + c = 0 are given by the well-known formula:

    x = (-b+/-sqrt(b^2-4ac)/2a

    so you normally get two solutions. But if the bit in the sqrt is zero, you only get one.

    That bit, b^2 - 4ac , is called the discriminant.

    So what do you have to change the coefficients to, in order to make the discriminant zero? You can change one of a, b or c at a time.
    Thanks for the help I can remember doing something like that.
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    (Original post by Mathsgu)
    Thank you! Could I ask how you got to those answers?
    I think I worked out how to do it now
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    (Original post by Mathsgu)
    The question is:

    Change one value in the equation so that there is one solution

    2xsquared + 7x + 3 =0

    Give as many possible solutions as you can.
    you just need to make b^2 - 4ac = 0, and you will have one solution.
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    (Original post by rock_climber86)
    you just need to make b^2 - 2ac = 0, and you will have one solution.
    Thanks, I didn't realise how easy it was!
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    (Original post by Mathsgu)
    Thanks, I didn't realise how easy it was!
    no worries. Interesting question btw. Never seen one like that before!
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    (Original post by rock_climber86)
    you just need to make b^2 - 2ac = 0, and you will have one solution.
    Watch out it's b^2-4ac=0

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    (Original post by Pungolini)
    Watch out it's b^2-4ac=0

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    Thanks for the correction! Innocent typo
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    b^2-4ac=0
    Plug in two different values at a time and solve for the remaining variable.
    eg. 7^2-4*2*c = 0 so c = 49/8
    Repeat for b and a.
 
 
 
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