SOLUTION: Directions are to Solve and I don't even know where to start. I thought to set the equation equal to zero, but very confused, can someone please help me?? w^2 - 7w - 18 = 0

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Directions are to Solve and I don't even know where to start. I thought to set the equation equal to zero, but very confused, can someone please help me?? w^2 - 7w - 18 = 0      Log On


   

Question 242758: Directions are to Solve and I don't even know where to start. I thought to set the equation equal to zero, but very confused, can someone please help me??
w^2 - 7w - 18 = 0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

w%5E2-7w-18=0 Start with the given equation.


Notice that the quadratic w%5E2-7w-18 is in the form of Aw%5E2%2BBw%2BC where A=1, B=-7, and C=-18


Let's use the quadratic formula to solve for "w":


w+=+%28-B+%2B-+sqrt%28+B%5E2-4AC+%29%29%2F%282A%29 Start with the quadratic formula


w+=+%28-%28-7%29+%2B-+sqrt%28+%28-7%29%5E2-4%281%29%28-18%29+%29%29%2F%282%281%29%29 Plug in A=1, B=-7, and C=-18


w+=+%287+%2B-+sqrt%28+%28-7%29%5E2-4%281%29%28-18%29+%29%29%2F%282%281%29%29 Negate -7 to get 7.


w+=+%287+%2B-+sqrt%28+49-4%281%29%28-18%29+%29%29%2F%282%281%29%29 Square -7 to get 49.


w+=+%287+%2B-+sqrt%28+49--72+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-18%29 to get -72


w+=+%287+%2B-+sqrt%28+49%2B72+%29%29%2F%282%281%29%29 Rewrite sqrt%2849--72%29 as sqrt%2849%2B72%29


w+=+%287+%2B-+sqrt%28+121+%29%29%2F%282%281%29%29 Add 49 to 72 to get 121


w+=+%287+%2B-+sqrt%28+121+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


w+=+%287+%2B-+11%29%2F%282%29 Take the square root of 121 to get 11.


w+=+%287+%2B+11%29%2F%282%29 or w+=+%287+-+11%29%2F%282%29 Break up the expression.


w+=+%2818%29%2F%282%29 or w+=++%28-4%29%2F%282%29 Combine like terms.


w+=+9 or w+=+-2 Simplify.


So the solutions are w+=+9 or w+=+-2