Solve th following quadratic equations using any method.
10,000x2 – 64 = 0
9x2 – 8 = — 34x
2x2 — 4x + 7 = 0
3.2x + 0.2x2 — 5 = 0
Thank you!
1. We can move 64 to the other side to get 10,000\(x^2\)=64. We then divide both sides by 10,000 to get 64/10000=\(x^2\)
we can then square root both sides to get 8/100=2/25.
2. We move 34x to the right side to get 9x^2+34x-8=0 you can then use the quadratic formula(or factor, I was just too lazy) to get x=-4, 2/9
3. You can also use the quadratic formula to get imaginary solutions. There are no real solutions to this one.
4. You can also use the quadratic formula to get -3.2 plus minus \( \sqrt{14.24}\) all over 4.
10000x^2 - 64 = 0 factor as a difference of squares
(100x - 8) (100x + 8) = 0
Set both factors to 0 and solve for x
100x - 8 = 0 100x + 8 = 0
100x = 8 100x = - 8
x = 8/100 = 2/25 x = -8/100 = -2/25
9x^2 - 8 = -34 rearrange as
9x^2 + 34x - 8 = 0 factor
(9x - 2) (x + 4) = 0
Set both factors to 0 and solve for x
9x - 2 = 0 x + 4 = 0
9x = 2 x = - 4
x = 2/9
2x^2 - 4x + 7 = 0 us the quadratic formula
x = 4 ± √ [ 4^2 - 4*2* 7 ] 4 ± √ [-40] 4 ± 2 i√ 10
________________ = __________ = _________ =
2 (2) 4 4
2 ± i√10
_______
2
3.2x + 0.2x^2 - 5 = 0 rearrange
0.2x^2 + 3.2x - 5 = 0 multiply through by 10
2x^2 + 32x - 50 = 0 divide through by 2
x^2 + 16x - 25 = 0 complete the square on x
x^2 + 16x + 64 = 25 + 64
(x + 8)^2 = 89 take both rots
x + 8 = ± √89
x = ± √89 - 8