help with some math questions? - XP Math - Forums

 XP Math - Forums help with some math questions?

 08-07-2007 #1 mike r Guest   Posts: n/a help with some math questions? 1. list all possible zeros of the following question:2x^4 - 3x^2 + -4=02. write as a sum of difference of logs of x,y, and zlog(x^5z^3/y^7)3. find the sum of the first 500 terms50,25,12.5,6.25,....4. left f(x)= 1/(x+5) and g(x) = (x +3)^1/2 find the domain of f+g,f-g,fg, and g/f
 08-07-2007 #2 Tony The Dad Guest   Posts: n/a #1) 2x^4 - 3x^2 + -4=02(xÂ²)Â² - 3xÂ² -4 = 0Substitute x^2 with q:2qÂ² - 3q - 4 = 0Use quadratic formula (using q instead of x)q = (-(-3)Â±âˆš((-3)Â²-4Â·2Â·(-4)))/(2Â·2) = (3 Â±âˆš(9+32))/4 = (3 Â±âˆš(41))/4Substitute xÂ² for q:xÂ² = (3 Â±âˆš(41))/4x = Â±âˆš((3 Â±âˆš(41))/4)You'll get 2 imaginary answers and 2 real answers.

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