A 1.

asked • 01/22/18

Solve with quadratic formula..7x^2 - 10x - 1 = 0?

7x2 - 10x - 1 = 0

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Bobosharif S. answered • 01/22/18

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7x2 - 10x - 1 = 0
One of the ways to solve by finding discriminant: D=b2-4ac.
a=7, b=-10, c=-1.
D=72-4*(-10)*(-1)=49-40=9>0. So, there exist two distinct solutions:
x1,2=(-b±√D)/2a
Now plug in values of a, b and D and find x1 and  x2
 
 
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A 1.

72 - 4(-10)(-1) instead of -102 - 4(7)(-1) ?
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01/23/18

Bobosharif S.

Yes, you are right. Good  job
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01/23/18

Bobosharif S.

It should be 
D=b2-4ac=|plug in b , a and c|= (-10)2-4*7(-1)=100+28=128=27=2*82
 
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01/23/18

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