某城區(qū)從某年開始的綠化總面積
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(萬平方米)與時間
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(年)的關系為
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.則該城區(qū)綠化總面積從4萬平方米到12萬平方米所用的時間為
年.(四舍五入取整)
解:因為從某年開始的綠化總面積
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(萬平方米)與時間
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(年)的關系為
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,即為8=
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則可以得到變量的差即為所求
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