The quadratic formula?

Question

6: 10x2 - 11 = 5x2 - 6x

{-3, 10}

{-11/5, 1}

{-3, -10}

{3, 5}

7: 2x2 - 3x - 1 = 0

2 ±√17

--------------------------------------...

4

3 ±√17

--------------------------------------...

3

3 ±√15

--------------------------------------...

4

3 ±√17

--------------------------------------...

4

8: 8x2 - 36 = 16x - 14

2 ±√13

--------------------------------------...

2

2 ±√15

--------------------------------------...

2

2 ±√15

--------------------------------------...

3

3 ±√15

--------------------------------------...

2

9: x2 - 2x - 3 = 0

{3}

{-3, 1}

{-3, 3}

{3, -1}

10: x2 + 5x - 31 = -35

{1, 9}

{4, 6}

{-1, -4}

{-4, 1}

Answer 1

If the expresson is ax² + bx + c, then

x = [– b ± √(b² – 4ac)] ÷ 2a

10x² – 11 = 5x² – 6x

15x² + 6x – 11 = 0

a = 15, b = 6, c= –11

x = [– 6 ± √36 + 660)] ÷ 30

x = [– 6 ± √696)] ÷ 30

x = [– 6 ± 26.38]/30

x = 20.38/30 or x = – 32.38/30

x =    0.67939 or x =    -1.0794

on this basis try to solve other

--------  

Answer 2

6.{-11/5, 1}

7 .3 ±√17

--------------------

         4

8.dunno

9.{3, -1}

10.{-1, -4}