SOLUTION: x^2 + 5x+ 4=0 answer:x=-1 or -4 need a full break down of how my text book got this answer

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Question 184812: x^2 + 5x+ 4=0

answer:x=-1 or -4
need a full break down of how my text book got this answer
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2B5x%2B4=0 Start with the given equation.


Notice we have a quadratic equation in the form of ax%5E2%2Bbx%2Bc where a=1, b=5, 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-%285%29+%2B-+sqrt%28+%285%29%5E2-4%281%29%284%29+%29%29%2F%282%281%29%29 Plug in a=1, b=5, and c=4


x+=+%28-5+%2B-+sqrt%28+25-4%281%29%284%29+%29%29%2F%282%281%29%29 Square 5 to get 25.


x+=+%28-5+%2B-+sqrt%28+25-16+%29%29%2F%282%281%29%29 Multiply 4%281%29%284%29 to get 16


x+=+%28-5+%2B-+sqrt%28+9+%29%29%2F%282%281%29%29 Subtract 16 from 25 to get 9


x+=+%28-5+%2B-+sqrt%28+9+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-5+%2B-+3%29%2F%282%29 Take the square root of 9 to get 3.


x+=+%28-5+%2B+3%29%2F%282%29 or x+=+%28-5+-+3%29%2F%282%29 Break up the expression.


x+=+%28-2%29%2F%282%29 or x+=++%28-8%29%2F%282%29 Combine like terms.


x+=+-1 or x+=+-4 Simplify.


So the answers are x+=+-1 or x+=+-4