If it's not what You are looking for type in the equation solver your own equation and let us solve it.
x in (-oo:+oo)
((2/3)*x^4)/5 < 2/3 // - 2/3
((2/3)*x^4)/5-(2/3) < 0
((2/3)*x^4)/5-2/3 < 0
2/15*x^4 < 2/3
2/15*x^4 < 2/3 // : 2/15
x^4 < 2/3/2/15
x^4 < 5
x^4 < 5 // ^ 1/4
abs(x) < 5^(1/4)
x in (-5^(1/4):5^(1/4))
x in (-5^(1/4):5^(1/4))
(-5^(1/4):5^(1/4))
| 450=b-21 | | 5(-3w-6)=4w-11 | | 8-3(p-4)=2pm | | 2sin(x)cos(x)=0 | | -20=5(f+3) | | x/3=6/9 | | 2/3x6/32/3 | | 27c^2=3c | | 2.5w=9 | | 1/4x=1/2-9 | | 10r+20=10r+20 | | 4=9m+49 | | 4.5=56 | | 3x-23=1whatisx | | v-8(30+2)= | | X-1438=26000-y | | S+19=49 | | 9=56 | | 99+x=102 | | 7x+-4=-3 | | 22x+26=4x-13 | | 20+-1y=-4+1y | | 4d+9-d-8=d | | 9=x+(-2) | | x*.08=15000 | | R=15cm | | 12+x=-21 | | -10(x-2)=10 | | 4/7=y14 | | 20a^3b^4-40a^2b^3= | | v-(7998-2222)+2344344256788= | | 23.8=3.56 |