SOLUTION: Using the quadratic formula, solve the following equation for X. Express your solution both in radical format and as decimals rounded to two decimal places. 3x^2+9x=-4

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Using the quadratic formula, solve the following equation for X. Express your solution both in radical format and as decimals rounded to two decimal places. 3x^2+9x=-4      Log On


   

Question 151911: Using the quadratic formula, solve the following equation for X.
Express your solution both in radical format and as decimals rounded to two decimal places.
3x^2+9x=-4
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

3x%5E2%2B9x=-4 Start with the given equation.


3x%5E2%2B9x%2B4=0 Add 4 to both sides.


Notice we have a quadratic equation in the form of ax%5E2%2Bbx%2Bc where a=3, b=9, and c=4


Let's use the quadratic formula to solve for x


x+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29 Start with the quadratic formula


x+=+%28-%289%29+%2B-+sqrt%28+%289%29%5E2-4%283%29%284%29+%29%29%2F%282%283%29%29 Plug in a=3, b=9, and c=4


x+=+%28-9+%2B-+sqrt%28+81-4%283%29%284%29+%29%29%2F%282%283%29%29 Square 9 to get 81.


x+=+%28-9+%2B-+sqrt%28+81-48+%29%29%2F%282%283%29%29 Multiply 4%283%29%284%29 to get 48


x+=+%28-9+%2B-+sqrt%28+33+%29%29%2F%282%283%29%29 Subtract 48 from 81 to get 33


x+=+%28-9+%2B-+sqrt%28+33+%29%29%2F%286%29 Multiply 2 and 3 to get 6.


x+=+%28-9%2Bsqrt%2833%29%29%2F%286%29 or x+=+%28-9-sqrt%2833%29%29%2F%286%29 Break up the expression.


So our answers are x+=+%28-9%2Bsqrt%2833%29%29%2F%286%29 or x+=+%28-9-sqrt%2833%29%29%2F%286%29


which approximate to x=-0.543 or x=-2.457