20x2 + 31x + 12 = 0 Solve the equation by factoring?
回答 (3)
2009-08-16 10:39 am
✔ 最佳答案
20x^2 + 31x + 12 = 0 (4x+3)(5x+4)=0
4x+3=0 5x+4=0
4x=-3 5x=-4
x=-3/4 x=-4/5
x={-3/4,-4/5} answer//
2009-08-18 1:44 pm
20x^2 + 31x + 12 = 0
20x^2 + 16x + 15x + 12 = 0
(20x^2 + 16x) + (15x + 12) = 0
4x(5x + 4) + 3(5x + 4) = 0
(5x + 4)(4x + 3) = 0
5x + 4 = 0
5x = -4
x = -4/5 (-0.8)
4x + 3 = 0
4x = -3
x = -3/4 (-0.75)
â´ x = -4/5 (-0.8), -3/4 (-0.75)
20x^2 + 16x + 15x + 12 = 0
(20x^2 + 16x) + (15x + 12) = 0
4x(5x + 4) + 3(5x + 4) = 0
(5x + 4)(4x + 3) = 0
5x + 4 = 0
5x = -4
x = -4/5 (-0.8)
4x + 3 = 0
4x = -3
x = -3/4 (-0.75)
â´ x = -4/5 (-0.8), -3/4 (-0.75)
2009-08-16 5:35 pm
( 4x + 3 ) ( 5 x + 4 ) = 0
x = - 3/4 , x = - 4/5
x = - 3/4 , x = - 4/5
收錄日期: 2021-05-01 12:43:30
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090816022815AAZV6sT