A^2+b^2=c^2 and for the radios try 4
The fact that the coefficients are pairwise identical (except for sign) tells you that x^2 -1 is a factor (and x-5 is the other factor). Of course, you recognize x^2-1 as a special form (the difference of squares) that is factored as (x +1)(x -1).
The zeros are x = -1, +1, +5.
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A graphing calculator confirms this.
You need to look at this as a proportion and ratio.
If
seventh graders were chosen, that is
of them.
You need to find
of the sixth graders to remain constant.
of 160 = 8 students.