x^2-20=x( x to the second power minus 20 equals)?
回答 (5)
2009-11-09 1:53 pm
✔ 最佳答案
x^2 - 20 = x or x^2 - x - 20 = 0 can be solved by factoring the left side.(x -5)(x+4) = 0 implies that x = 5, -4 are the solutions.
2009-11-09 10:04 pm
x^2 - 20 = x
x^2 - x - 20 = 0
x^2 + 4x - 5x - 20 = 0
(x^2 + 4x) - (5x + 20) = 0
x(x + 4) - 5(x + 4) = 0
(x + 4)(x - 5) = 0
x + 4 = 0
x = -4
x - 5 = 0
x = 5
â´ x = -4, 5
x^2 - x - 20 = 0
x^2 + 4x - 5x - 20 = 0
(x^2 + 4x) - (5x + 20) = 0
x(x + 4) - 5(x + 4) = 0
(x + 4)(x - 5) = 0
x + 4 = 0
x = -4
x - 5 = 0
x = 5
â´ x = -4, 5
2009-11-09 9:57 pm
Is your problem x^2 - 20 = x? If so, then subtract x from both sides to get:
x^2 - x - 20 = 0. Factor. Find two numbers that when multiplied together = - 20 and when added equals - 1, the implied number in front of the middle term, x.
Try - 5 and + 4.
(x - 5)(x + 4) = 0. Set each binomial = 0 and solve for x.
x - 5 = 0. x = 5.
x + 4 = 0. x = - 4.
Answer: x = 5, x = 4
x^2 - x - 20 = 0. Factor. Find two numbers that when multiplied together = - 20 and when added equals - 1, the implied number in front of the middle term, x.
Try - 5 and + 4.
(x - 5)(x + 4) = 0. Set each binomial = 0 and solve for x.
x - 5 = 0. x = 5.
x + 4 = 0. x = - 4.
Answer: x = 5, x = 4
參考: Self
2009-11-09 9:55 pm
Either x^2 - 20 = 0 or x = 1 So x = rt20 or -rt20 or 1.
[I assume you typed the problem correct]
[I assume you typed the problem correct]
2009-11-09 9:52 pm
(x+sqr(20))(x-sqr(20)) you should simplify further
收錄日期: 2021-05-01 12:50:45
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091109054638AAOvWiO