Someone please help me

If f(x)=x^3 and g(x)=2x+7 when g(x)=-5

What are the soultion(s) to the quadratic equation 40- x^2=0

Of the ones listed here, the factor that had the greatest impact on the eventual destruction of native americans' ways of life was the development of the a) automobile. b) highway. c) railroad. d) steamboat.