Perform the indicated elementary row operations in the stated order

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

Solve the equation by completing the square. x^2+2x=17

Find the condition that the zeros of the polynomial f(x) = x^3+3px^2+3px+r may be in a.p.