This topic contains 6 replies, has 5 voices, and was last updated by ÜberMathGuru 2 years, 5 months ago.
Please help me on this. On my homework I have the problem
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This topic contains 6 replies, has 5 voices, and was last updated by ÜberMathGuru 2 years, 5 months ago.
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February 23, 2012 at 5:07 pm #428 Close  Stick (to front)  Merge  Trash  Spam  Reply  
kelman90 Member

Given x^2+bx+2c=0 What value in terms of c must b have to make this expression a perfect square? 
March 7, 2012 at 10:48 am #455 Move  Split  Trash  Spam  Reply  
Yeah Member

polonium210 is a radioactive element with a halflife of 140 days. This means that half of the polonium decays every 140 days. If 400 mg is the initial sample how much is left after 700 days? 
March 7, 2012 at 10:48 am #456 Move  Split  Trash  Spam  Reply  
Yeah Member

and what is the formula? 
March 13, 2012 at 6:44 pm #471 Move  Split  Trash  Spam  Reply  
ÜberMathGuru Member

Yeah, Sorry for the delayed response! The basic equation for half life is AT = A0 2^(T/H) where A0 is the initial radioisotope’s activity, AT is the decayed activity after time T, and H is the halflife. These values in your problem would be: A0=400 mg and AT is what they are asking for. AT=400x[2^(700/140)]=400×2^(5)= 400x (1/2^32) = 400/32= 12.5 mg 
March 16, 2012 at 9:00 pm #478 Move  Split  Trash  Spam  Reply  
butler Member

what are all the variables of a graph 
March 21, 2012 at 8:05 pm #487 Move  Split  Trash  Spam  Reply  
ÜberMathGuru Member

(x^2y^4)^2=x^4y^8 Always multiply the outer exponent by the exponent of each factor (or by both the exponent of the numerator and the denominator if it is a ratio)!!!! 
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