## Algebra and Trigonometry 10th Edition

Solutions: $x=2$ $x=-1$
Notice that: $-7x^3=x^3-8x^3$ $x^6-7x^3-8=0$ $x^6+x^3-8x^3-8=0$ $x^3(x^3+1)-8(x^3+1)=0$ $(x^3-8)(x^3+1)=0$ $x^3-8=0$ $x^3=8$ $x=\sqrt[3] 8=2$ or $x^3+1=0$ $x^3=-1$ $x=\sqrt[3] {-1}=-1$ Check the solutions: $x=2$: $2^6-7(2)^3-8=64-7(8)-8=64-56-8=0$ $x=-1$: $(-1)^6-7(-1)^3-8=1-7(-1)-8=1+7-8=0$