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whadduptori

  • 3 years ago

Use the quadratic formula to solve the equation? 4x2 – 6x – 10 = 0 is anybody able to show me work?

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  1. Rezz5
    • 3 years ago
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    the quadratic formula is -b (±)Sqrt[b-4ac]/2a\[-b \pm \frac{ \sqrt{b-4ac}}{ 2a}\]

  2. Rezz5
    • 3 years ago
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    where ax^2 +bx +c just substitute and you will get your answer.

  3. jim_thompson5910
    • 3 years ago
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    \[\Large x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}\] \[\Large x = \frac{-(-6)\pm\sqrt{(-6)^2-4(4)(-10)}}{2(4)}\] \[\Large x = \frac{6\pm\sqrt{36-(-160)}}{8}\] I'll let you finish.

  4. whadduptori
    • 3 years ago
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    I have all that work! I just get confused with the last part? like would i subtract 36-(-160)

  5. Rezz5
    • 3 years ago
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    36--160? well double negative is positive, so? 36+160

  6. jim_thompson5910
    • 3 years ago
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    36-(-160) is the same as 36+160

  7. whadduptori
    • 3 years ago
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    so it would become 196?

  8. jim_thompson5910
    • 3 years ago
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    it would

  9. whadduptori
    • 3 years ago
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    |dw:1352933217966:dw|

  10. whadduptori
    • 3 years ago
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    so would that be the answer?

  11. jim_thompson5910
    • 3 years ago
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    you can keep going and there's a +- between the 6 and square root

  12. jim_thompson5910
    • 3 years ago
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    you should have \[\Large x = \frac{6\pm\sqrt{196}}{8}\] but you can keep going

  13. Rezz5
    • 3 years ago
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    (6*14)/8 =(3*14)/4 =(3*7)/2 =21/2

  14. whadduptori
    • 3 years ago
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    yes i have that!

  15. Rezz5
    • 3 years ago
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    okay, what is wrong?

  16. whadduptori
    • 3 years ago
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    wait where did you get the 6*14/8

  17. jim_thompson5910
    • 3 years ago
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    the square root of 196 is 14, so... \[\Large x = \frac{6\pm\sqrt{196}}{8}\] becomes \[\Large x = \frac{6\pm14}{8}\]

  18. Rezz5
    • 3 years ago
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    above is very clear and correct, so first you do the plus sign which is (6+14)/8 this is ONE OF YOUR x's the you do (6-14)/8 this is your other x value so your x values are: 5/2 and -1

  19. whadduptori
    • 3 years ago
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    THank you so much! I didnt know how to find that! but you just made it clear for me! thank you both for your help! (:

  20. Rezz5
    • 3 years ago
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    your most welcome,

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