All Junior Cert Mathematics posts
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    Quatratic equations so52307

    The study clix only showed some of the formulas... But if a long question pops up, i don't get it.

    Heres the question, can you solve it for me?

    A positive number is squared and three times the number is then added. The result is 88. Find the number.

    1. avatar image

      aoifehayes

      x^2+3x=88

      x^2+3x-88

      can you take it from here?

    2. avatar image

      DylanLynch

      I find putting it down in words first helps me out. Think about what EXACTLY they're asking. If you have a number and you multiply it by itself (ie; squaring it) and then add on your starting number 3 times you'll get 88.

      Next write it down equation-wise (User aoifehayes has it done already).

      Now you can use factorising OR the "-b method" to find values for x.

      Sub back in your values for x to make sure they work (ie; the left side of the equals sign equals the right side of the equals sign) and voila! Solved.

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      Art1998

      I use the big X method, its extremely handy once you get used to it. Look it up online.

    4. avatar image

      Art1998

      X2 + 3x=88......... X2+3x-88= 0, now you have a quadratic an should be able to solve it with whatever formula you usually use

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      Me

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