Is the solution to the equation (x^2 - 9) + (2x + 5) - 4 = 0 is also the solution to the equation |x^2 - 9| + |2x + 5| - 4 = 0?
If not, why not? Please explain.
Maths Equation?
2015-10-25 12:58 am
回答 (2)
2015-10-25 8:49 am
The answer is "No".
As the solution to the equation (x² - 9) + (2x + 5) - 4 = 0 is -4 or 2.
But, the solution to the equation |x² - 9| + |2x + 5| - 4 = 0 is (1 - √19).
They have different solution(s).
As the solution to the equation (x² - 9) + (2x + 5) - 4 = 0 is -4 or 2.
But, the solution to the equation |x² - 9| + |2x + 5| - 4 = 0 is (1 - √19).
They have different solution(s).
2015-10-25 1:08 am
Sol
(x^2－9)+(2x+5)－4=0
x^2+2x－8=0
(x－2)(x+4)=0
x=2 or x=－4
when x=2
｜x^2－9｜+｜2x+5｜－4=｜4－9｜+｜4+5｜－4=5+9－4=10<>0
So
x=2 is not the equation of ｜x^2－9｜+｜2x + 5｜－4=0
(x^2－9)+(2x+5)－4=0
x^2+2x－8=0
(x－2)(x+4)=0
x=2 or x=－4
when x=2
｜x^2－9｜+｜2x+5｜－4=｜4－9｜+｜4+5｜－4=5+9－4=10<>0
So
x=2 is not the equation of ｜x^2－9｜+｜2x + 5｜－4=0
收錄日期: 2021-04-18 13:57:52
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151024165804AAIF5gj