If a1+2a2+3a3=1, where a1,a2&a3 are all positive numbers; then what is the minimum value of 2a1+4a2+8a3?
If a1,a2,a3,a4 are the coefficients of any four
consecutive terms in the expansion of (1+x)n, then
a1a1+a2 + a3a3+a4 =