SOLUTION: Hi, I am having trouble solving quadratic equations. I get down to the bottom of the problem and do not know how to reduce, or I do not get a perfect square because i made an erro

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Question 409321: Hi, I am having trouble solving quadratic equations. I get down to the bottom of the problem and do not know how to reduce, or I do not get a perfect square because i made an error somewhere. Would you please look at my work and help me?
Solving by -b sqrt (b^2-4ac)/(2a)
20y^2+17y-10=0
x= -17 sqrt ((17)^2-4(20(-10)/(2(20))
x = -17 sqrt +-(289-(-800))/(40)
x = -17 sqrt +-(1089)/(40)
x = -17 sqrt +- ((9)(121))/(40)
x = -17 3 sqrt+- (121)/(40) What to do here?
thanks

Answer by jsmallt9(3758) (Show Source):
You can put this solution on YOUR website!
You are pretty close. Other than not finishing, the only mistake is that your "+-" is in the wrong place. It belongs in front of the square root. The Quadratic Formula is:

With the "+-" in the right place, you are totally correct up to:

Next we use a property of radicals, , to split the square root of the product into the product of the square roots of the factors:

Now, just like you had, . What you didn't realize is that 121 is also a perfect square! so . Replacing these square roots with these whole numbers we get:

which simplifies to:

This is as far was we can go with the "+-". Next we write this "the long way":
or
Simplifying each we get:
or
or