Question

*Will fan and medal!* Solve. x2 – 8x + 4 = 0

A. http://static.k12.com/calms_media/media/241000_241500/241312/1/5d12906023b147e1093cbb1770227a619653973f/05_14_UT_4c.gif
B. http://static.k12.com/calms_media/media/241000_241500/241310/1/fbf7ccf657b5ddacb447bef49f5f8329fe32ced2/05_14_UT_4b.gif
C. http://static.k12.com/calms_media/media/241000_241500/241309/1/42574ac77f550c2ec2f194a7857c87eac12252a9/05_14_UT_4a.gif
D. http://static.k12.com/calms_media/media/241000_241500/241308/1/8415df7fce37bb79e9f5e5393d21d1c659e2b97c/05_14_UT_4_bd.gif

Answer 1

Do you know the formula to solve any quadratic?

Answer 2

^

Answer 3

Can you explain it to me?

Answer 4

\[\frac{-b \pm \sqrt{b ^{2}-4ac}}{2a}\]
In your quadratic:
a = 1
b = -8
c = 4
If you plug these values into the formula, the two solutions will be found. Can you do that?

Answer 5

\[x=\frac{-(-8) \pm \sqrt{64-16}}{2}=you\ can\ calculate\]

Answer 6

D is the answer... by solving the quadratic

Answer 7

\[x = -b \pm \sqrt{b ^{2}-4ac} \div 2a\]

Answer 8

I would add 12 to both sides and complete the square. This is almost always the easiest way when the coefficient of x^2 is 1 and the coefficient of x (looking at ax^2+bx+c=0 ) is even, unless you are able to factor which is not your case.