Oblicz wartość wyrażenia: [latex]3 sqrt{5}( sqrt{5} + x) -2x( x^{2} - 3 sqrt{5} ) [/latex] dla x= -[latex] sqrt{5} [/latex] Dziękuję ;)

[latex]3sqrt{5}(sqrt{5}+x)-2x(x^{2}-3sqrt{5})= 15+3sqrt{5}x-2x^{3}+6sqrt{5}x=\\=-2x^{3}+9sqrt{5}x+15[/latex] [latex]dla x = -sqrt{5}\\=-2(-sqrt{5})^{3}+9sqrt{5}(-sqrt{5})+15=10sqrt{5}-45+15=10sqrt{5}-30[/latex] Lub: [latex]3sqrt{5}(sqrt{5}-sqrt{5})-2(-sqrt{5})[(-sqrt{5})^{2}-3sqrt{5}] = 0+2sqrt{5}(5-3sqrt{5}) =\\=10sqrt{5}-30[/latex]