I've been on an online calculator to see how this is calculated but I don't understand it.
The equation is:
2x^2 + 30x + 112 = 0
Can't work out how to solve this by factorisation.
Steps and solutions would be great, thank you!
Solve this equation by factorisation?
2020-09-10 11:14 pm
回答 (4)
2020-09-10 11:25 pm
2x² + 30x + 112 = 0
(2x² + 30x + 112)/2 = 0
x² + 15x + 56 = 0
(x + 7)(x + 8) = 0
x + 7 = 0 or x + 8 = 0
x = -7 or x = -8
(2x² + 30x + 112)/2 = 0
x² + 15x + 56 = 0
(x + 7)(x + 8) = 0
x + 7 = 0 or x + 8 = 0
x = -7 or x = -8
2020-09-11 12:06 am
2x^2 + 30x + 112 = 0
x^2 + 15x + 56 = 0
Experiment with the factors of 56 until you find two that sum to 15.
x^2 + 7x + 8x + 56 = 0
x(x + 7) + 8(x + 7) = 0
(x + 8)(x + 7) = 0
x^2 + 15x + 56 = 0
Experiment with the factors of 56 until you find two that sum to 15.
x^2 + 7x + 8x + 56 = 0
x(x + 7) + 8(x + 7) = 0
(x + 8)(x + 7) = 0
2020-09-10 11:30 pm
Here is how I would do it.
(1) divide both sides by 2
x^2 + 15x + 56 = 0
(2) Make a note of 1/2 of the middle term, which is 7.5x
(3) Add 7.5^2 to both sides
x^2 + 15x + 7.5^2 + 56 = 7.5^2
(4) The first three terms are a perfect square
(x + 7.5)^2 + 56 = 7.5^2
(5) Subtract 56 from both sides
(x + 7.5)^2 = 7.5^2 - 56 = 0.25 = 0.5^2
(6) So then (x+7.5) = +/- 0.5
(7) x = +0.5 - 7.5, or x = -0.5 -.7.5
x = -7 or -8
(8) the original equation is equivalent to
2 (x+7) (x+8) = 0
(1) divide both sides by 2
x^2 + 15x + 56 = 0
(2) Make a note of 1/2 of the middle term, which is 7.5x
(3) Add 7.5^2 to both sides
x^2 + 15x + 7.5^2 + 56 = 7.5^2
(4) The first three terms are a perfect square
(x + 7.5)^2 + 56 = 7.5^2
(5) Subtract 56 from both sides
(x + 7.5)^2 = 7.5^2 - 56 = 0.25 = 0.5^2
(6) So then (x+7.5) = +/- 0.5
(7) x = +0.5 - 7.5, or x = -0.5 -.7.5
x = -7 or -8
(8) the original equation is equivalent to
2 (x+7) (x+8) = 0
收錄日期: 2021-04-24 08:00:42
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https://hk.answers.yahoo.com/question/index?qid=20200910151458AAP76Nc