SOLUTION: Use the quadratic formula to solve the equation. x^2 - 3x = -4

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Use the quadratic formula to solve the equation. x^2 - 3x = -4      Log On


   

Question 317009: Use the quadratic formula to solve the equation.
x^2 - 3x = -4
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

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


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


Notice that the quadratic x%5E2-3x%2B4 is in the form of Ax%5E2%2BBx%2BC where A=1, B=-3, 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-%28-3%29+%2B-+sqrt%28+%28-3%29%5E2-4%281%29%284%29+%29%29%2F%282%281%29%29 Plug in A=1, B=-3, and C=4


x+=+%283+%2B-+sqrt%28+%28-3%29%5E2-4%281%29%284%29+%29%29%2F%282%281%29%29 Negate -3 to get 3.


x+=+%283+%2B-+sqrt%28+9-4%281%29%284%29+%29%29%2F%282%281%29%29 Square -3 to get 9.


x+=+%283+%2B-+sqrt%28+9-16+%29%29%2F%282%281%29%29 Multiply 4%281%29%284%29 to get 16


x+=+%283+%2B-+sqrt%28+-7+%29%29%2F%282%281%29%29 Subtract 16 from 9 to get -7


x+=+%283+%2B-+sqrt%28+-7+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%283+%2B-+i%2Asqrt%287%29%29%2F%282%29 Simplify the square root


x+=+%283%2Bi%2Asqrt%287%29%29%2F%282%29 or x+=+%283-i%2Asqrt%287%29%29%2F%282%29 Break up the expression.


So the solutions are x+=+%283%2Bi%2Asqrt%287%29%29%2F%282%29 or x+=+%283-i%2Asqrt%287%29%29%2F%282%29