3x^2-4x=6.67?

Answer 1

3x² - 4x = 6.67

3x² - 4x - 6.67 = 0

Use the quadratic form, this is:

x = -B +/- [{sqrt (B² - 4AC)} / 2A]

when

Ax² + Bx + C = 0

3x² - 4x - 6.67 = 0

A=3, B=(-4), C=(-1)

then:

x = 4 +/- [ [sqrt(16-4*{3}*{-6.67})] / 2*(3)]
x = 4 +/- [{sqrt(96.04)} / 6]
x = 4 +/- [ 9.8 / 6 ]

x1 = 2.3
x2 = -0.967

Enjoy it.

Answer 2

Much more direct approach:
3x^2 - 4x - 6.67 = 0
Use the quadratic formula which says:
If ax^2 + bx + c = 0 then
x = [-b +/- sqrt(b^2-4ac)] / 2a, thus
x = [4 +/- sqrt(16-4(3)(-6.67))] / 2(3)
x = [4 +/- sqrt(96.04)] / 6
x = [4 +/- 9.8] / 6
so there are two answers:
x = (4+9.8)/6 = 2.3 or
x = (4-9.8)/6 = -0.96667

Answer 3

3x² - 4x - 6.67 = 0
3x² - 4x - 20/3 = 0
9x² - 12x - 20 = 0
x = [12 ±√(144 + 720) ] /18
x = [12 ± √864 ] /18
x = 2.3 , x = - 0.97