- four *x^ four *exp(-x^ four) + E^(-x^ four) = zero
minus 4 multiply by x to the power of 4 multiply by exponent of ( minus x to the power of 4) plus E to the power of ( minus x to the power of 4) equally 0
minus four multiply by x to the power of four multiply by exponent of ( minus x to the power of four) plus E to the power of ( minus x to the power of four) equally zero