Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What is the HCF ofacx³ + bcx² + adx² + acdx + bdx + bcd and adx³ + acx² + bdx² + bcx + acdx + bcd if HCF (c, d) = 1, c ≠d?
 If the median of observations 12, 1, 8, 54, 61, 28, 45, 35, 21, 17 is M, then what is the value of 2M + 5 ?