Solving Multi-Step Linear Equations and Compound Inequalities

You are right up until the very last step shaniab29544.  On the next to last step you have x3 = 9.  Because the 3 comes after the x we assume this means x to the power 3 (at least that is what heureka and I have assumed), so x-cubed = 9.  This means that x is the cube root of 9 or ³√9.  

If you prefer to interpret this as just x times 3 then we would have x times 3 = 9 so that x would be 9 divided by 3, or x = 3.

.

What is the solution to the equation 1−5(x3+x2)=-5x2−4(x3+2) ?

$$\small{\text{$ \begin{array}{rcl} 1-5(x^3+x^2) &=& -5x^2-4(x^3+2) \\\\ 1-5(x^3+x^2) + 5x^2 +4(x^3+2) &=& 0\\\\ 1 - 5x^3 - 5x^2 + 5x^2 + 4x^3 + 8 &=& 0 \\\\ -5x^3 - 5x^2 + 5x^2 + 4x^3 + 9 &=& 0 \\\\ -5x^3 \underbrace{- 5x^2 + 5x^2}_{=0} + 4x^3 + 9 &=& 0 \\\\ -5x^3 + 4x^3 + 9 &=& 0 \\\\ -x^3 + 9 &=& 0 \\\\ 9 &=& x^3 \\\\ x^3 &=& 9 \qquad | \qquad \sqrt[3]{}\\\\ x &=& \sqrt[3]{9}\\\\ x &=& 2.0800838231 \end{array} $}}\\\\ \mathbf{ x = 2.0800838231 }$$

Another beautifully presented answer.  Thank you Heureka  

it wrong

What makes you think it's wrong shaniab29544?  

heureka has given the correct real number root (there are two other roots, but they are complex).

.

it like this  i think