SOLUTION: x^2+x-42=0

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Question 201632: x^2+x-42=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2Bx-42=0 Start with the given equation.


Notice that the quadratic x%5E2%2Bx-42 is in the form of Ax%5E2%2BBx%2BC where A=1, B=1, and C=-42


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-%281%29+%2B-+sqrt%28+%281%29%5E2-4%281%29%28-42%29+%29%29%2F%282%281%29%29 Plug in A=1, B=1, and C=-42


x+=+%28-1+%2B-+sqrt%28+1-4%281%29%28-42%29+%29%29%2F%282%281%29%29 Square 1 to get 1.


x+=+%28-1+%2B-+sqrt%28+1--168+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-42%29 to get -168


x+=+%28-1+%2B-+sqrt%28+1%2B168+%29%29%2F%282%281%29%29 Rewrite sqrt%281--168%29 as sqrt%281%2B168%29


x+=+%28-1+%2B-+sqrt%28+169+%29%29%2F%282%281%29%29 Add 1 to 168 to get 169


x+=+%28-1+%2B-+sqrt%28+169+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-1+%2B-+13%29%2F%282%29 Take the square root of 169 to get 13.


x+=+%28-1+%2B+13%29%2F%282%29 or x+=+%28-1+-+13%29%2F%282%29 Break up the expression.


x+=+%2812%29%2F%282%29 or x+=++%28-14%29%2F%282%29 Combine like terms.


x+=+6 or x+=+-7 Simplify.


So the solutions are x+=+6 or x+=+-7