SOLUTION: please please help me! i know the quadratic formula, but what i dont understand is what do you do if there is no 'b' for the quadratic formula? for example: normal formula: ax2

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Question 612240: please please help me! i know the quadratic formula, but what i dont understand is what do you do if there is no 'b' for the quadratic formula? for example:
normal formula:
ax2+bx+c
question
4p2-36=0
Answer by bucky(2189) (Show Source):
You can put this solution on YOUR website!
If you are trying to solve a standard quadratic equation of the form:
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and you notice that there is no term containing x, then you can use the quadratic formula if you just set b equal to zero. For the example problem you gave:
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by comparing this to the standard quadratic equation, you can see that a = 4, b = 0, and c = -36. Then by the quadratic formula you can say that:
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and substituting the values we identified for a, b, and c we get:
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Notice that there is no "b" term before the radical in the numerator. Also there is no b^2 term in the radical. So the numerator is just the radical which is preceded by a + and - sign, and the radical contains just the product -4 times 4 times -36. And the denominator is 2*4 which is 8. So the answer is:
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Doing the multiplication within the radical results in :
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The square root of 576 is 24, so the answer becomes:
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And dividing it out results in:
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And don't forget the + and - signs to give you p = +3 and -3.
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But there is even an easier way to do this example problem ... with fewer chances for error because there are less manipulations. Start with the problem as given:
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Notice that you can divide both sides (all terms) by 4 to get:
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Then get rid of the -9 on the left side by adding +9 to both sides as shown:
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Then take the square root of both sides to get the answers:
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and
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Hope this helps you to understand the problem a little better.
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