Questions on Algebra: Quadratic Equation answered by real tutors!

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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: 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(9217) About Me  (Show Source):
You can put this solution on YOUR website!

3x^2+9x=-4 Start with the given equation.


3x^2+9x+4=0 Add 4 to both sides.


Notice we have a quadratic equation in the form of ax^2+bx+c where a=3, b=9, and c=4


Let's use the quadratic formula to solve for x


x = (-b +- sqrt( b^2-4ac ))/(2a) Start with the quadratic formula


x = (-(9) +- sqrt( (9)^2-4(3)(4) ))/(2(3)) Plug in a=3, b=9, and c=4


x = (-9 +- sqrt( 81-4(3)(4) ))/(2(3)) Square 9 to get 81.


x = (-9 +- sqrt( 81-48 ))/(2(3)) Multiply 4(3)(4) to get 48


x = (-9 +- sqrt( 33 ))/(2(3)) Subtract 48 from 81 to get 33


x = (-9 +- sqrt( 33 ))/(6) Multiply 2 and 3 to get 6.


x = (-9+sqrt(33))/(6) or x = (-9-sqrt(33))/(6) Break up the expression.


So our answers are x = (-9+sqrt(33))/(6) or x = (-9-sqrt(33))/(6)


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