Answers to first 5 of 15 – Self assessment questions on Quadratic equations: Question 3

What must be added to the expression 2x² – 3x to make it a perfect square? Click here to get the question

Solution

2x² – 3x

Step1

Since the coefficient of x² is 2, we first divide through by 2 to make the coefficient of x² to be 1

2x²/2– ^3x/₂

= x² – ^3x/₂

Step2

What must be added is the square of half of the coefficient of x, which is -³/₂

Half the coefficient and square it as follows

-³/₂* ^1/₂ = -³/₂₄

Square of the halved coefficient is (^-3/₄)² = ⁹/₁₆

Thus, ⁹/₁₆ must be added toto make it a perfect square

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