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Use the quadratic formula to solve x² + 8x + 9 = 0. What are the solutions to the equation? Round irrational solutions to the nearest tenth.  
x=−1.2 and x=−6.8
x = 1 and x=−9
x=−6.6 and x=−1.4
x=−1 and x=−8

Respuesta :

DABasaur

the answer is .C..........

isyllus

Answer:

The solution set is x=-6.6 and x=-1.4

Option 3 is correct.

Step-by-step explanation:

Given: [tex]x^2+8x+9=0[/tex]

Formula: [tex]x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex]

For given equation, [tex]x^2+8x+9=0[/tex]

a=1 , b=8 and c=9

Substitute the value of a, b and c into quadratic formula.

[tex]x=\dfrac{-8\pm\sqrt{8^2-4\cdot 1\cdot 9}}{2(1)}[/tex]

[tex]x=\dfrac{-8\pm\sqrt{64-36}}{2}[/tex]

[tex]x=\dfrac{-8\pm\sqrt{28}}{2}[/tex]

[tex]x=\dfrac{-8\pm2\sqrt{7}}{2}[/tex]

[tex]x=-4\pm \sqrt{7}[/tex]

[tex]x=-4-2.65\approx -6.6[/tex]

[tex]x=-4+2.65\approx -1.4[/tex]

Hence, The solution set is x=-6.6 and x=-1.4

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