How do you solve x2+8x2=0 using completing the square?

3 Answers
Jun 18, 2018

Solution: x=(4+32),x=(432)

Explanation:

x2+8x2=0orx2+8x=2 or

x2+8x+16=2+16 or

(x+4)2=18or(x+4)=±18 or

x+4=±32orx=4±32

Solution: x=(4+32),x=(432)[Ans]

Jun 18, 2018

Take the second coefficient, divide it by 2, and square it, to complete the square, and obtain the solutions:
x=4+18 and x=418

Explanation:

To complete the square, take the second coefficient (the one next to the x), divide it by 2, and square it. This will give you the number you need to complete the square.
In this case, that would be (8÷2)2=16

Add this number to both sides of the original equation:
(x2+8x+16)2=16
(x+4)22=16
(x+4)2=18

This gives us 2 possible solutions:
x+4=±18

x=4±18

Jun 18, 2018

x=4±32

Explanation:

add 2 to both sides

x2+8x=2

add (12coefficient of the x-term)2 to both sides

x2+2(4)x+16=2+16

(x+4)2=18

take the square root of both sides

(x+4)2=±18note plus or minus

x+4=±18=±9×2=±32

subtract 4 from both sides

x=4±32exact values

x8.24 or x0.24 to 2 dec. places