Q&A If x > 0, y>0, z>0, such that x^2+y^2+z^2=1, find the minimum value of \dfrac{5-8xy}{z} . Inequality

Q&A A car travels 240 km in 4 hours. How long does it take the same car to travel 480 km? Ratio and Proportion

Q&A The average of 5 consecutive odd numbers is 21. Find the smallest odd number. Arithmetic sequence