how can we resould this equation? y= -o,1 xX4+ 1,2 x

how can we resould this equation? y= -o,1 x^4+ 1,2 x

$y=-0.1x^4+1.2x$
is a function equation.
Your graph has zeros, extrema, and inflection points.

zeros

$-0.1x^4+1.2x=0$

$-0.1x^3+1.2=0\\\color{blue}x_1=0\\x^3=\frac{-1.2}{-0.1}=12$

$x_2=\sqrt[3]{12}=2.289$

extrema

$y\ '=-0.4x^3+1.2=0\\x_{max}^3=\sqrt[3]{\frac{-1.2}{-0.4}}=\sqrt[3]{3}$

$x_{max}=\sqrt[3]{3}=1.442$

$y=-0.1x^4+1.2x$

  !