|ax+b|≤9的解為-2≤x≤4,求a,b為何 |3x+a|≥b的解為x ≤5或x≥11,求a,b為何 |ax+3|>b的解為x<-1或x>9,求a,b為何 要有算式謝謝😁😁😁?

2016-08-04 8:17 am

回答 (1)

2016-08-04 8:35 am
1 |ax+b|≤9的解為-2<=x<=4,求a-b為何
Sol
-2<=x<=4
-3<=x-1<=3
|x-1|<=3
|3x-3|<=9
|-3x+3|=|3x-3}<=9
(a,b)=(-3,3) or (a,b)=(3,-3)
2 |3x+a|≥b的解為x <=5或x>=11,求a,b為何
Sol
x<=5 or x>=11
x-8<=-3 or x-8>=3
|x-8|>=3
|3x-24|>=9
(a,b)=(-24,9)

3 |ax+3|>b的解為x<-1或x>9,求a,b為何
Sol
x<-1 or x>9
x-4<-5 or x-4>5
|x-4|>5
|-x+4|>5
|-3x+12|>15
|-3x/4+3|>15/4
(a,b)=(-3/4,15/4)


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