SOLUTION: x^2-4x-5=0

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Question 397042: x^2-4x-5=0
Found 2 solutions by jim_thompson5910, robertb:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2-4x-5=0 Start with the given equation.


Notice that the quadratic x%5E2-4x-5 is in the form of Ax%5E2%2BBx%2BC where A=1, B=-4, and C=-5


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


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


x+=+%284+%2B-+sqrt%28+16-4%281%29%28-5%29+%29%29%2F%282%281%29%29 Square -4 to get 16.


x+=+%284+%2B-+sqrt%28+16--20+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-5%29 to get -20


x+=+%284+%2B-+sqrt%28+16%2B20+%29%29%2F%282%281%29%29 Rewrite sqrt%2816--20%29 as sqrt%2816%2B20%29


x+=+%284+%2B-+sqrt%28+36+%29%29%2F%282%281%29%29 Add 16 to 20 to get 36


x+=+%284+%2B-+sqrt%28+36+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%284+%2B-+6%29%2F%282%29 Take the square root of 36 to get 6.


x+=+%284+%2B+6%29%2F%282%29 or x+=+%284+-+6%29%2F%282%29 Break up the expression.


x+=+%2810%29%2F%282%29 or x+=++%28-2%29%2F%282%29 Combine like terms.


x+=+5 or x+=+-1 Simplify.


So the solutions are x+=+5 or x+=+-1

If you need more help, email me at jim_thompson5910@hotmail.com

Also, feel free to check out my tutoring website

Jim

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
(x -5 )(x + 1) = 0 ==> x = 5,-1.