Complete the square to disarm!f(x) = 4x2 + 16x - 7
No need to worry I remember how to complete the square
OH NO!
First, we must factor the first two terms by ‘a’, the coefficient of x2, in this case, 4.
Complete the Square to Disarm
= 4x2 + 16x - 7
1 2 34 5 67 8 9
= 4(x2 + 4x) - 7
Next we mentally divide the coefficient of x by 2 (4÷2=2), and square it (22=4). Now that we have this number, we add and subtract it inside the brackets.
Complete the Square to Disarm
= 4(x2 + 4x + 4 - 4) = 7
1 2 34 5 67 8 9
= 4(x2 + 4x) - 7
Oh! And because we are both adding and subtracting, nothing in the brackets change!
Next we must remove the -4 from inside the bracket
Enter the Completed Square to Disarm f(x) =4 (x + 2)2 -23
= 4(x2 + 4x + 4 - 4) = 7
= 4(x + 2)2 - 7 - 16
1 2 34 5 67 8 9
To bring the new term that is being subtracted outside of the bracket, we multiply it by ‘a’, in this case, 4. ex (4 x -4 = -16). Lastly, collect like terms (-7 - 16 = -23)
Quick Max, Grab something, we need to get out of here.