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The roots of 7x^2 + x - 5 = 0 are a and b. Compute 1/a + 1/b.

 Feb 11, 2022
 #1
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Use Vieta's calcs

 

ab = -5/7

a+b = -1/7

 

 

1/a + 1/b      multiply first term by b/b    second term by  a/a

 

b/ab  +  a/ab  =  ( b + a )/ab    sub in the red values above

             

1/a + 1/b   =  (-1/7) / (-5/7 ) =  1/5

 Feb 11, 2022

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