SOLUTION: Solve each equation by using the quadratic formula. 30. -3x^2 - 2x - 5 = 0

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Question 170969: Solve each equation by using the quadratic formula.
30. -3x^2 - 2x - 5 = 0

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:


Starting with the general quadratic


ax%5E2%2Bbx%2Bc=0


the general solution using the quadratic equation is:


x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29




So lets solve -3%2Ax%5E2-2%2Ax-5=0 ( notice a=-3, b=-2, and c=-5)





x+=+%28--2+%2B-+sqrt%28+%28-2%29%5E2-4%2A-3%2A-5+%29%29%2F%282%2A-3%29 Plug in a=-3, b=-2, and c=-5




x+=+%282+%2B-+sqrt%28+%28-2%29%5E2-4%2A-3%2A-5+%29%29%2F%282%2A-3%29 Negate -2 to get 2




x+=+%282+%2B-+sqrt%28+4-4%2A-3%2A-5+%29%29%2F%282%2A-3%29 Square -2 to get 4 (note: remember when you square -2, you must square the negative as well. This is because %28-2%29%5E2=-2%2A-2=4.)




x+=+%282+%2B-+sqrt%28+4%2B-60+%29%29%2F%282%2A-3%29 Multiply -4%2A-5%2A-3 to get -60




x+=+%282+%2B-+sqrt%28+-56+%29%29%2F%282%2A-3%29 Combine like terms in the radicand (everything under the square root)




x+=+%282+%2B-+2%2Ai%2Asqrt%2814%29%29%2F%282%2A-3%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)




x+=+%282+%2B-+2%2Ai%2Asqrt%2814%29%29%2F%28-6%29 Multiply 2 and -3 to get -6




After simplifying, the quadratic has roots of


x=-1%2F3-sqrt%2814%29%2F3%2Ai or x=-1%2F3%2Bsqrt%2814%29%2F3%2Ai