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一个两位数,个位上的数字比十位上的数字大5,如果将它们的位置交换,所得的新数比原来的两位数大45,求原来的两位数是多少?

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答案(点此获取答案解析)

解:设十位上的数字为x,个位上的数字为y,

根据题意得: {yx=510y+x

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    The plants grown by Wageningen University researchers in Mars-like soil back in March have been analyzed and the results are excellent: at least four of the crops do not contain harmful heavy metal levels and are perfectly safe to eat, the University researchers report.

    If you've seen The Martian, you can remember how much Matt Damon got done living off of his poo-powered crop of potatoes. It just goes to show how important it is for a long-term colony to be able to grow their own food locally. We've taken one step closer to that goal in March, when Netherlands' Wageningen University reported that they've managed to grow ten different crops in Mars-like soil.

    However, growing food doesn't do us much good if eating it kills us, and researchers were worried that these crops contained dangerous heavy metals like lead or cadmium(镉) from the martian soil. But future colonists are delighted, as lab analysis of the crops determined that at least four of them are safe to eat.

    Led by ecologist Wieger Wamelink, the team tested radishes, tomatoes, rye, and peas. They looked at cadmium, lead, aluminium(铝), nickel(镍), copper, chrome(铬), iron, arsenic(砷), manganese(锰), and zinc(锌) contents in the plants, and didn't find any in dangerous levels. In fact, some of these vegetables have lower levels of heavy metals than those grown in regular potting soil. The plants were also tested for vitamins, alkaloids(生物碱), and flavonoids(类黄酮), with good results. While there are six more crops to test, Wamelink himself said that the results up to now are “very promising.”

    “Growing food locally is especially important to our mission of permanent settlement, as we have to ensure sustainable food production on Mars. The results of Dr. Wamelink and his team at Wageningen University & Research are significant progress towards that goal,” said Mars One co-founder and CEO Bas Lansdorp in a press release.

    A crowdfunding campaign is underway (and will be until the end of August) to fund the test of the remaining crops, potatoes included. If all the crops test out safe, with concentrations of heavy metal the FDA and the Dutch Food Agency consider as safe, Wamelink's team will host a “Martian dinner” at the Wageningen greenhouse. But I've seen the movie. Stay clear of the potatoes.