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2 votes
After completing the square, what are the solutions to the quadratic equation

below?
x^2 - 7x+9 = 4​

2 Answers

2 votes

Answer:

x=7/2+square29/2

Explanation:

I’m guessing this is right using the top answer because the test doesn’t have the answer flipped like that.

User Noby
by
5.3k points
4 votes

Answer:


x_1= \frac{\sqrt{{29}}}{2} +(7)/(2)\\\\x_2= -\frac{\sqrt{{29}}}{2} +(7)/(2)

Explanation:

1. Subtract 9 from both sides of the equation:


x^2 - 7x+9-9 = 4-9\\\\x^2 - 7x= -5

2. Notice that the coefficient of "x" is 7. Then:


((7)/(2))^2=(49)/(4)

3. Add
(49)/(4) to both sides of the equation:


x^2 - 7x+(49)/(4)= (49)/(4)-5\\\\x^2 - 7x+(49)/(4)= (29)/(4)

4. Completing the square, you get:


(x -(7)/(2))^2= (29)/(4)

5. To find the solutions, you must square-root both sides of the equation, simplify, and solve for "x". Then, you get:


\sqrt{(x -(7)/(2))^2}= \±\sqrt{(29)/(4)}\\\\x -(7)/(2)=\±\frac{\sqrt{{29}}}{2} \\\\x= \±\frac{\sqrt{{29}}}{2} +(7)/(2)\\\\\\x_1= \frac{\sqrt{{29}}}{2} +(7)/(2)\\\\x_2= -\frac{\sqrt{{29}}}{2} +(7)/(2)

User Alberto Perrella
by
5.8k points