How do you answer this?

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2 Answers
Jan 31, 2018

x=4+19 and x=419

Explanation:

Using complete the square:

Half term of x

82=4x

Put inside bracket and square it, adding on the constant.

(x4)23

Take away the squared number of the term of x in the bracket:

(x4)2163

Collect like terms

163=19

(x4)219

This is the completed the square format, but now we solve.

(x4)219=0

Add 19

(x4)2=19

Get rid of the squared bracket, by square rooting 19.

Remember the ±

x4=±19

Add 4

x=4±19

This means the answer will be either x=4+19 and x=419 as we usually have 2 solutions.

Feb 6, 2018

x=4±19

Explanation:

solve using the method of completing the square

x28x3=0

the coefficient of the x2 term must be 1 which it is

add/subtract (12coefficient of the x-term)2 to
x28x

x2+2(4)x+16163=0

(x4)219=0

(x4)2=19

take the square root of both sides

(x4)2=±19note plus or minus

x4=±19

add 4 to both sides

x=4±19exact values