0.275≤(0.7a+0.02b)/(a+b)≤0.281.4≤a+b≤1.5求a和b的取值范围12.75≤ 34a/(a+b)≤13倒过来1/12.75≤ 1/34+b/34a ≤1/13错了吧1/12.75>1/13的吧

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0.275≤(0.7a+0.02b)/(a+b)≤0.281.4≤a+b≤1.5求a和b的取值范围12.75≤ 34a/(a+b)≤13倒过来1/12.75≤ 1/34+b/34a ≤1/13错了吧1/12.75>1/13的吧
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0.275≤(0.7a+0.02b)/(a+b)≤0.281.4≤a+b≤1.5求a和b的取值范围12.75≤ 34a/(a+b)≤13倒过来1/12.75≤ 1/34+b/34a ≤1/13错了吧1/12.75>1/13的吧
0.275≤(0.7a+0.02b)/(a+b)≤0.28
1.4≤a+b≤1.5
求a和b的取值范围
12.75≤ 34a/(a+b)≤13
倒过来
1/12.75≤ 1/34+b/34a ≤1/13
错了吧1/12.75>1/13的吧

0.275≤(0.7a+0.02b)/(a+b)≤0.281.4≤a+b≤1.5求a和b的取值范围12.75≤ 34a/(a+b)≤13倒过来1/12.75≤ 1/34+b/34a ≤1/13错了吧1/12.75>1/13的吧
0.275≤(0.7a+0.02b)/(a+b)≤0.28
两遍除以0.02
13.75≤ (34a+a+b)/(a+b)≤14
两边减1
12.75≤ 34a/(a+b)≤13
倒过来
1/12.75≤ 1/34+b/34a ≤1/13
两边减1/34再乘以34
85/51≤ b/a ≤ 21/13
两边乘以a
85a/51≤ b ≤ 21a/13
当b=21a/13时
1.4≤34a/13≤1.5
此时91/170≤a≤39/68,147/170≤b≤63/68
当b=85a/51时
1.4≤136a/51≤1.5
此时357/850≤a≤153/272,7/10≤b≤255/272
各取极限值
357/850≤a≤39/68,7/10≤b≤63/68
额.差不多就这意思.思路.主要是思路.