SOLUTION: My book says the answer is -5 and -3, where am I missing it?
{{{x^2-8x-15=0}}}
x={{{(-(-8)+- sqrt(-8^2-4*1*15))/(2*1)}}}
x={{{8+- sqrt (64-60)/(2)}}}
x={{{8+- sqrt (4)/(2)}}}
Algebra ->
Quadratic Equations and Parabolas
-> SOLUTION: My book says the answer is -5 and -3, where am I missing it?
{{{x^2-8x-15=0}}}
x={{{(-(-8)+- sqrt(-8^2-4*1*15))/(2*1)}}}
x={{{8+- sqrt (64-60)/(2)}}}
x={{{8+- sqrt (4)/(2)}}}
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You can put this solution on YOUR website! My book says the answer is -5 and -3, where am I missing it? , assume the equation should be x^2 - 8x + 15
x=
x=
x=
:
Th book is wrong, this would factor to:
(x-5)(x-3) = 0
which is:
x=5,x=3
I think you aren't being careful with your signs and
with putting parentheses around what you are substituting.
If your book says the solutions are -5 and -3, then you
have typed one or two signs wrong in the original problem,
or else the book has a typographical error, and sometimes
they do.
You gave the problem as
but the solutions to that are not -5 and -3.
You would have to have had this problem instead
[not as the other tutor said.]
In order to get solutions -5 and -3.
Then you would factor and get
and then you'd set each of those = 0 and get
x+5=0 x+3=0
x=-5 x=-3
But let's suppose it was as you thought
You have this:
x=
x=
x=
x=
x=
Then you'd factor 2 out of the top:
x=
and then cancel the 2's
x=
Edwin
