Pull down resistor for multiplexer and decoder

Hi,
If we have 2 multiplexer which shares the same A,B,C lines. Which is the good practice to do with? Either pull down the each pin of multiplexer ( totally 6 resistors of 4.7k value - 3 for mux1 and 3 for mux2) or commonly pull down the lines ( totally 3 resistor of 10K value common to both mux )?

What about the case for decoder?

If the two multiplexors are close to each other, it is enough to use just the three resistors. There is no reason use a separate resistor on each pin. If they were very far apart, so that the high-frequency characteristics of the traces began to matter, then you might want to use separate resistors, but I can't imagine a practical circuit where that would be the case.

But I did notice that your values are backwards - using 4.7K when using 6 resistors versus using 10K when using 3 resistors. In the case of 6 resistors, each line (A, B, or C) has two pull-up resistors in parallel. If both those resistors are 4.7K, the effective pull-up resistance for the line would be 2.35K, while it would be 10K with three resistors. It would make more sense to use six 10K resistors or three 4.7K resistors. I vote for three 4.7K resistors.

Thanks..

I thought correctly as your mentioned values of 10K for 6 resistor and 4.7K for 3 resistors but by mistake i typed wrongly.

By the way the distance between them is around 50 cm.

What you meant by the high frequency characteristics of the trace? how it will require 6 resistors?

Similarly as two if we use 5 mux's then also shall we use same 4.7k commonly instead of separate 22k?

OK, you have multiplexors 50 cm. apart. I don't know why you are using pull-up resistors in the first place. Is the source of the A, B, and C lines an open collector? Given all the capacitance you have on those lines, it is unlikely that the rising edge (cause by the pull-up resistors) is going to be very fast. If it is a slow edge, then you wont have substantial reflections in a mere 50 cm. of wire or traces. If you do have reflections, then I would be much more worried about the falling edge than the rising edge. The falling edge is coming from whatever device is sourcing the A, B, and C lines. It probably has an output impedance much lower than 4.7K, so it will pull the lines low a lot faster than the pull-up resistors will pull them high. As for what value of pull-up to use, that depends on why you need pull-ups.