Question 451839
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Hi,
21x^2 - 6 = 15x 
21x^2 - 15x-6 = 0
factoring
(7x +2)(3x -3) = 0  |  Note:SUM of the outside terms(-21x) and the inside terms(6x) = -15x
check the factoring using the FOIL method of multiplying binomials
F	First terms
O	Outside terms
I	Inside terms
L	Last terms
(7x +2)(3x -3) = 0 
(7x +2)= 0  x = -2/7
(3x -3) = 0  x = 1
 x = -2/7,1