Saturday
May 25, 2013

# Posts by Kong

Total # Posts: 24

Algebra 3
(x^2-1)<8 (x+3)(x-3)<8 -3<x<3

chemistry(rusting)
i know that metal placed in more acidic solution will produce rust faster.but why metal placed near the sea shore will easily have rust?the wind with moisture which contains salt solution,right? however ,i have a problem.When i put the metal in the test tube with sodium chlor...

chemistry
pH value is higher,the more acidic the solution.

chemistry(rusting)
thx for your teaching first.however ,i have a problem.When i put the metal in the test tube with sodium chloride solution,it rust slower than the one i put in distilled water with air,why?

chemistry(rusting)
i know that metal placed in more acidic solution will produce rust faster.but why metal placed near the sea shore will easily have rust?the wind with moisture which contains salt solution,right?

Math
ans: take square root[(8.3/tan60)^2 + 8.3^2] (Pyth.thm) =9.58m

chemistry(rusting)
i know that iron(II)hydroxide is brown solid,how about iron(III)oxide?

chemistry(rusting)
Why metal(eg. iron)placed at aqueous solution will be more easily occur rusting?Is it due to the mobile ions in the aqueous solution ?Please give me an detail explanation ,thank you.

cal
The circumference of a sphere was measured to be 86.000 cm with a possible error of 0.5 cm. Use linear approximation to estimate the maximum error in the calculated surface area and Estimate the relative error in the calculated surface area.

cal
Let f(x)=-5e^(x+1)+e^8 . find f'(0)

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