solve x-3x(x+6)=2x-9?

Answer 1

x - 3x(x)-3x(6) = 2x-9
x - 3x^2-18x = 2x-9
-17x - 3x^2 = 2x-9

*Set the equation to "0" - add 9 to both sides (when you move a term to the opposite side, always use the opposite sign).

-17x - 3x^2+9 = 2x-9+9
-17x - 3x^2+9 = 2x (subtract 2x from both sides).
-17x - 3x^2+9-2x = 2x-2x
-19x - 3x^2+9 = 0
- 3x^2-19x+9 = 0
3x^2+19x-9 = 0

First: use the Quadratic Formula which, is....
x = [-b +/- V`b^2 - 4ac] / 2a

Sec: substitute the terms with the corresponding variables... a = 3; b = 19; c = -9

x = [-19 +/- V`19^2 - 4(3)(-9)] / 2(3)

x = [-19 +/- V`19*19 - 4(3)(-9)] / 6

x = [-19 +/- V`361 - 12(-9)] / 6

x = [-19 +/- V`361 - (-108)] / 6

x = [-19 +/- V`361 + 108] / 6

x = [-19 +/- V`469] / 6

P.S. the solution doesn't need to be in decimal form, unless your teachers asks you to do so.

Answer 2

x - 3x(x + 6) = 2x - 9

x - 3x² - 18x = 2x - 9

Subtract 2x - 9 from both sides

- 3x² - 19x + 9 = 0

multiply thru by -1

3x² + 19x - 9 = 0

Solve with quadratic formula

x = (-b ± √(b² - 4ac))/2a

x = (-19 ± √(361 + 108))/6

x = (-19 ± √469)/6

x = (-19 ± 21.66)/6

x = 0.4427, x=-6.777
.

Answer 3

x-3x(x+6) = 2x-9
x - 3x^2 - 18x = 2x - 9
-3x^2 - 19x + 9 = 0

Use quadratic formula:

(19 +/- sqrt(19^2 - 4*(-3)*(9))) / 2(-3)
(19 +/- 21.656) / -6
=0.443 or -6.776

Answer 4

x - 3x^2-18x = 2x - 9
-3x^2 + 19x = -9

-3x^2 + 19x + 9 = 0

Use quadratic formula now, since you can't factor that.

x = -b +- sqrt (b^2 - 4ac) / 2a
= -19 +- sqrt (19^2 - 4(-3)(9))/-6
= -19 +- sqrt (361+108)/-6
= -19 +- 21.65 /-6

Root 1:

x= -0.44


Root 2:

x= 6.77

Answer 5

im not so good at math but ill give it a try
x=-15

Answer 6

Why should I?