Need help with all three problems

7.8 Show that the Gamma and Weibull distributions both include the Ex- ponential as a special case by taking a = 1. 7.9 Show that the uniform, normal, double exponential, and Cauchy densities are all symmetric about their midpoints. 7.10 A distribution is called unimodal if the density has exactly one absolute maximum. Show that the normal, exponential, double exponential, Cauchy, Gamma, Weibull, and Lognormal are unimodal. 7.8 Show that the Gamma and Weibull distributions both include the Ex- ponential as a special case by taking a = 1. 7.9 Show that the uniform, normal, double exponential, and Cauchy densities are all symmetric about their midpoints. 7.10 A distribution is called unimodal if the density has exactly one absolute maximum. Show that the normal, exponential, double exponential, Cauchy, Gamma, Weibull, and Lognormal are unimodal