Question

Please help 50 point !!

Answer 1

The last one

Explanation:

Subtract 1 from both sides

simplify

simplify

Answer 2

The last one

Explanation:

`x^3+1=0`

Subtract 1 from both sides

`x^3+1-1=0-1`

simplify

`x^3=-1`

`\mathrm{For\:}x^3=f\left(a\right)\mathrm{\:the\:solutions\:are\:}x=\sqrt[3]{f\left(a\right)},\:\sqrt[3]{f\left(a\right)}(-1-√(3)i)/(2),\:\sqrt[3]{f\left(a\right)}(-1+√(3)i)/(2)`

`x=\sqrt[3]{-1},\:x=\sqrt[3]{-1}(-1+√(3)i)/(2),\:x=\sqrt[3]{-1}(-1-√(3)i)/(2)`

simplify

`x=-1,\:x=(1)/(2)-i(√(3))/(2),\:x=(1)/(2)+i(√(3))/(2)`

(That's basically the last one but in a different way of writing it)