SOLUTION: Here is one that I am completely stumped on: Find a value for k that will make 4x^2 + 6.4x +k a perfect square. Describe the procedure that you used which requires algebra, not

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Question 173656: Here is one that I am completely stumped on:
Find a value for k that will make 4x^2 + 6.4x +k a perfect square. Describe the procedure that you used which requires algebra, not trial and error.
HELP!!!
Found 2 solutions by vleith, Fombitz:
Answer by vleith(2983) (Show Source):
You can put this solution on YOUR website!
For a perfect square, the form is

So let's get the original equation in the correct form

Now use the values in your eqaution and set them equal to the ones that make up the 'correct form'

{{k/4 = B^2}}

Now just grind that out and check your answer

Answer by Fombitz(32388) (Show Source):
You can put this solution on YOUR website!
A perfect square would mean,

If we expand the right hand side, we get,

Let's compare coefficients with your equation,
1.
2.
3.
From 1, a can be either 2 or -2.
Let's start with a=2 and find the others,
From 2,

From 3,

.
.
.
We can also work with a=-2.
From 2,

From 3,

And we're led to the same answer.