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How to solve which number completes the square of the expression belo? 2x^2-3x+ 1. 9/8 2. 9 3. -9/2 4. 9/16

User Eric Harms
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1 Answer

5 votes

Answer: 1.
(9)/(8) .

Explanation:

The given expression
2x^2-3x+1

Using completing the square method.

First, we divide the entire expression by 2 and write in the form of
x^2+bx=c , we get


x^2-(3)/(2)x+(1)/(2)

Such that
b=(3)/(2)\ \ \ , c=(1)/(2)

Now add and subtract
((b)/(2))^2 on both sides.


((b)/(2))^2=(((3)/(2))/(2))^2\\\\=((3)/(2*2))^2\\\\=((3^2)/(4^2))\\\\=(9)/(8)

Here, we add and subtract
(9)/(8) .

Hence, the correct answer is 1.
(9)/(8) .

User Confusified
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