Long N. answered • 06/14/15
Tutor
4.3
(3)
Mechanical engineer
-12 +- √144 - 4*(12)*(2)
--------------------------
-18
--------------------------
-18
I think you should plug in -9 instead of 12 where I underlined/make bold. Everything else looks good though.
Long N.
You can calculate the value of x buy punching each of the equation (the + and the - one) into a calculator
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06/14/15
Michael J.
After the last step you have, simplify the square-root part of the function first. Then, divide each term above the line by -18. Don't forget, there is a plus/minus sign in the formula, so you will have two solutions.
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06/14/15
JOHN F.
Long N., remember that the quadratic formula is for ax2 + bx + c = 0. Billy substituted correctly when he wrote
-12 +- √144 - 4*(-9)*(2) || -12+-√[144 +(-4)(-9)(2)] -12+-√[144 + 72]
-------------------------- || = ------------------------------- = ----------------------- =
-18 || -18 -18
-------------------------- || = ------------------------------- = ----------------------- =
-18 || -18 -18
-12+-√[216] -12+-6√6 -6(2+-√6) 1(2+-√6) 2+-√6
---------------- = -------------- = --------------- = ------------- = -------------
-18 -18 -18 3 3
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06/15/15
Long N.
I know, he fixed it before you comment
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06/15/15
Casey W.
tutor
You don't need any more steps, unless asked for a decimal approximation of the solutions...you found both answers to the question using the QF, namely
x=(2-\sqrt(6))/3 and x=(2+\sqrt(6))/3...that's it, you are done...go to the next problem :)
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06/15/15
Billy J.
06/14/15