Maths Chapter Test!!(急!!)plz

1.) At least what should be added to 20 to make it a triangular number?

2.) The first four pentagonal numbers can be expressed as follows:

The first: 1=1

The second: 5=2+3

The third: 12=3+4+5

The fourth: 22=4+5+6+7

Find the seventh and eighth pentagonal numbers.

3.) A shop owner buys 100 eggs at $40. If 30% of the eggs are broken and the rest are all sold at $0.5 each,find the profit or loss percent.

1 個解答

評分
  • 匿名
    1 十年前
    最愛解答

    1. 1

    2. the seventh: 19+20+21+22+23+24+25=154

    the eighth: 26+27+28+29+30+31+32+33=236

    3. The loss percent:

    =<40-[100*(1-30%)*0.5]>/40*100%

    =5/40*100%

    =1/8*100%

    =12.5%

    <大括號>

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