Question 147533: write the equation x(x-15)+56=0 in quadratic form and then solve it by factoring
Found 2 solutions by stanbon, Electrified_Levi:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! write the equation x(x-15)+56=0 in quadratic form and then solve it by factoring
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x^2-15x+56 = 0
(x-7)(x-8) = 0
x = 7 or x = 8
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Cheers,
Stan H.
Answer by Electrified_Levi(103) (Show Source):
You can put this solution on YOUR website! Hi, hope I can help
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write the equation x(x-15)+56=0 in quadratic form and then solve it by factoring
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First, you have to use distributive property
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Next, you have to find the factors of this number.
(x )(x ) = 0
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Since the last number is positive, we know that both the signs have to be the same, either positive or negative. Since the middle number is negative, we know that the signs are negative(the factors of 56 have to add up to be a -15, if you add two negatives, the answer will be negative)
(x - )(x - ) = 0
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Now we need to find all the factors of 56, they have to add up to -15
1. (56)(1)
2. (28)(2)
3. (14)(4)
4. (8)(7)
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We find out that the fourth answer, (8)(7), is the answer( (-8)+(-7) = -15)(We already have the negative signs in place).
(x - 8)(x - 7) = 0
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Now we can solve for "x", we need to look at the factors seperately, and then solve for "x".
1.
(x - 8) = 0
x - 8 = 0
x - 8 + 8 = 0 + 8
x - 0 = 8
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x = 8( one of the answers)
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Now we will solve for the other answer
2.
(x - 7) = 0
x - 7 = 0
x - 7 + 7 = 0 + 7
x - 0 = 7
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x = 7( The second answer)
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We can check our answers by putting our numbers in place of "x" in the original equation.
x(x-15)+56=0, We will replace "x" with 8
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8(8-15)+56=0
8(-7) + 56 = 0
(-56) + 56 = 0, ( True)
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Now we will replace "x" with 7
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7(7-15)+56=0
7(-8) + 56 = 0
(-56) + 56 = 0, (True)
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The answers are 8, and 7.
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Hope I helped, Levi
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