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Which equation shows the quadratic formula used correctly to solve 7x2 = 9 + x for x?

Which equation shows the quadratic formula used correctly to solve 7x2 = 9 + x for-example-1
User Iqueqiorio
by
8.0k points

2 Answers

1 vote

Answer:

The answer is the D :)

User Lubiluk
by
8.4k points
4 votes

Answer:


x=\frac{1\pm\sqrt{(-1)^(2)+4(7)(9)}} {2(7)}

Explanation:

we know that

The formula to solve a quadratic equation of the form


ax^(2) +bx+c=0

is equal to


x=\frac{-b\pm\sqrt{b^(2)-4ac}} {2a}

in this problem we have


7x^(2) -x-9=0

so


a=7\\b=-1\\c=-9

substitute in the formula


x=\frac{-(-1)\pm\sqrt{-1^(2)-4(7)(-9)}} {2(7)}


x=\frac{1\pm\sqrt{(-1)^(2)+4(7)(9)}} {2(7)}


x=\frac{1\pm√(253)} {14}

User Andy Holaday
by
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