Whar number must be added to both sides of the equation to solve it by completeing the square? 3x^2+15x=9
(1)225
(2)25
(3)6.25
(4)5
first divide all terms by 3 to get
x^2 + 5x = 3
x^2 + 5x + 25/4 = 3 + 25/4
and I know 25/4 = 6/25
clearly I meant to type
nd I know 25/4 = 6.25
To solve the equation 3x^2 + 15x = 9 by completing the square, you need to add a certain number to both sides of the equation. This number is obtained by taking half of the coefficient of the x-term (which is 15) and squaring it:
Step 1: Take half of the coefficient of the x-term: 15/2 = 7.5
Step 2: Square the result: 7.5^2 = 56.25
Therefore, the number you need to add to both sides of the equation is 56.25.
Now let's check the answer choices:
(1) Adding 225 to both sides of the equation would not give you the correct result.
(2) Adding 25 to both sides of the equation would also not give you the correct result.
(3) Adding 6.25 to both sides of the equation does give you the correct result.
(4) Adding 5 to both sides of the equation would not give you the correct result.
Thus, the correct answer is (3) 6.25.