Answer:
-2 <= x <= 1/3
Step-by-step explanation:
it is the same as for equations.
the solution for a square equation is
x = (-b ± sqrt(b² - 4ac))/(2a)
our parameters here are
a = 3
b = 5
c = -2
so,
x = (-5 ± sqrt(25 - -24))/6 = (-5 ± sqrt(49))/6 = (-5 ± 7)/6
x1 = (-5 + 7)/6 = 2/6 = 1/3
x2 = (-5 - 7)/6 = -12/6 = -2
since we are looking for smaller or equal, points of 0 will be part of the solution.
now we need to check each side of these points on the x-axis, if they are true or not to the inequality.
left of -2 : let's pick -3
3×(-3)² + 5×-3 -2 = 3×9 - 15 - 2 = 27 - 15 -2 = 10
this is NOT <= 0, so this interval does not fit.
similar, right of 1/3 : let's pick 1
3×1² + 5×1 - 2 = 3 + 5 - 2 = 6
this is NOT <= 0, so this interval does not fit either (as expected, as normally either both sides fit, or both fail).
lastly, in the middle between -2 and 1/3 : let's pick 0
3×0² + 5×0 - 2 = -2
this IS <= 0, so the interval between -2 and 1/3 fits.
