SOLUTION: Algebraically find the EXACT ROOTS in simplest form for: x/-7=(x+1)/(x-11)

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Question 177920: Algebraically find the EXACT ROOTS in simplest form for: x/-7=(x+1)/(x-11)
Answer by gonzo(654) About Me  (Show Source):
You can put this solution on YOUR website!
this equation doesn't have any roots.
when you solve for the roots you get a complex number.
complex number means there are no roots.
here's how i did it.
your equation is:
%28x%2F-7%29+=+%28x%2B1%29%2F%28x-11%29
muiltiply both sides by -7 to get:
x+=+-7+%2A+%28x%2B1%29%2F%28x-11%29
multiply both sides by (x-11) to get:
x+%2A+%28x-11%29+=+-7+%2A+%28x%2B1%29
simplify to get:
x%5E2+-+11x+=+-7x+-+7
add 7x to both sides to get:
x%5E2+-+11x+%2B+7x+=+-7
add 7 to both sides to get":
x%5E2+-+11x+%2B+7x+%2B+7+=+0
simplify to get:
x%5E2+-+4x+%2B+7+=+0
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you can solve this using the quadratic formula or completing the squares.
either way will get you the same answer.
i'll use the quadratic formula first:
a = 1 = coefficient of the x^2 term.
b = -4 = coefficient of the x term.
c = 7 = constant term.
quadratic formula is:
x+=+%28-b+%2B-+sqrt%28b%5E2-4ac%29%2F%282a%29%29
substituting values for a,b,c gets:
x+=+%28-%28-4%29+%2B-+sqrt%28%28-4%29%5E2+-+4%2A7%2A1%29%2F%282%2A1%29%29
this becomes:
x+=+4+%2B-+sqrt%2816+-+28%29%2F%282%29
which becomes:
x+=+4+%2B-+sqrt%28-12%29%2F%282%29
which becomes:
x+=+4+%2B-+sqrt%28-3%2A2%2A2%29+%2F+%282%29+
which becomes:
+x+=+4+%2B-+2%2Asqrt%28-3%29%2F%282%29
which becomes:
+x+=+2+%2B-+sqrt%28-3%29
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you can also solve this by completing the squares as follows:
your equation after manipulating it is:
x%5E2+-+4x+%2B+7+=+0
this is the same place where we solved it using the quadratic formula.
this time, however, we will complete the squares.
subtract 7 from both sides to get:
x%5E2+-+4x+=+-7
x%5E2+-+4x+=+%28x-2%29%5E2+-+4
your equation becomes:
%28x-2%29%5E2+-+4+=+-7
you add 4 to both sides to get:
%28x-2%29%5E2+=+-3
you take the square root of both sides to get:
x-2 = +/- sqrt%28-3%29
you add 2 to both sides to get:
x+=+2+%2B-+sqrt%28-3%29
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since the value of x is a complex number, this means that there are no roots to the equation.
since the roots are when the equation crosses the x-axis, this means that this equation does not cross the x-axis.
a graph of x%5E2-4x%2B7 is shown below:
graph%28800%2C800%2C-20%2C20%2C-20%2C20%2Cx%5E2-4x%2B7%29