This is simply done by Method of Completing the Square.
3x - x²
Add and subtract half the coefficient of x and square it.
( This is done so there'd be no alterations to the quadractic Expression)
So To start
We'd like x² to be positive...(So factor out a negative).
–(x² - 3x )
Now In this case
You see there's a Negative Outside the the bracket
Instead of adding and Subtracting squared values of half the coefficient of X... We'd Add Twice and do not subtract.
Reason: If you add outside the bracket and subtract the other inside the bracket... This will be wrong because there's a negative patiently waiting outside the bracket to Interact with the negative you subtracted to make it Positive.
See what I mean.
Let's say you added 2² and subtracted 2² in this problem
2² – ( x² - 3x - 2²)
If you decide to open the bracket
You'll have
2² – x² + 3x + 2²
NOW THIS IS WRONG BECAUSE WE ALTERED THIS EXPRESSION. WHERE'D 2² + 2² COME FROM?
THIS IS WHY YOU'LL ADD THE SQUARED COEFFICIENT OF X TWICE IN CASES LIKE THESE.
SO GOING BACK TO THE ORIGINAL QUESTION.
– (x² - 3x )
Adding the half the coefficient of x twice and squaring them...
Coefficient of x = 3
Half of 3 = 3/2
Squaring it gives (3/2)²
NOW PROCEEDING
(3/2)² – [ x² - 3x + (3/2)²]
If you open this bracket... (3/2)² will cancel out with —(3/2)²
Meaning that we haven't altered the expression in any way
Moving On...
Applying basic factorizing principle
9/4 – ( x - 3/2)².
Answer = 9/4 – ( x - 3/2)² Which is in the Form m – ( x - n )²
Therefore m = 9/4 and n = 3/2.
Hope This Helps
