Eric Nicholas K's answer to Yos's Secondary 4 E Maths Singapore question.

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
1st
To complete the square, we perform the following.

1. Check whether the coefficient of x2 is 1 or not. If it's not 1, we must factor out the coefficient of x2 from the entire equation so that the new coefficient of x2 becomes 1. Here, it's already 1 so this step can be skipped.

2. Introduce a term equal to the square of half the coefficient of x, then return it immediately after. Here, the coefficient of x is -8. Half of it is -4 and its square is 16, so we must introduce 16 into the equation and return the 16 immediately after. The introduced 16 is meant to complete the square, while the returned 16 is to be evaluated together with the other constant numbers there.