Solve by completeing the square. 9x^2-12x=14.?
2008-06-01 8:12 am
I got the answer being (6 (+ or -)sqrt 50)/3. Is that right for my solutions ? thanks for the hlep guys
回答 (2)
2008-06-01 8:20 am
✔ 最佳答案
9x^2 - 12x = 149x^2 - 12x - 14 = 0
(3x - 2)^2 - 18 = 0
(3x - 2)^2 = 18
3x - 2 = ±√18
3x - 2 = ±4.24
3x - 2 = 4.24
3x = 4.24 + 2
3x = 6.24
x = 6.24/3
x = 2.08
3x - 2 = -4.24
3x = -4.24 + 2
3x = -2.24
x = -2.24/3
∴ x = 2.08 , -2.24/3
2008-06-01 4:24 pm
x² - (12/9) x = 14/9
x² - (4/3) x = 14/9
x² - (4/3) x + 4/9 = 14/9 + 4/9
(x - 2/3)² = 18/9
(x - 2/3) = ± â18 / 3
(x - 2/3) = ± 3â2 / 3
(x - 2/3) = ± â2
x = 2/3 ± â2
x² - (4/3) x = 14/9
x² - (4/3) x + 4/9 = 14/9 + 4/9
(x - 2/3)² = 18/9
(x - 2/3) = ± â18 / 3
(x - 2/3) = ± 3â2 / 3
(x - 2/3) = ± â2
x = 2/3 ± â2
收錄日期: 2021-05-01 10:37:27
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