Solve for x. Enter your answer in interval notation using grouping symbols. x^2+9x<-20

Which of the following is true for the relation f(x)=2x^2+1

He weights of 2-pound bags of best dog food are approximately normally distributed with a given mean  and standard deviation  according to the empirical rule, what percentage of the bags will have weights within 3 standard deviations of the mean? 47.5%68%95%99.7%

Events a and b are independent. the probability of a occurring is 2/5. the probability of b occurring is 1/4. what is p(a and b)?