# Year 2 Maths Differentiation Help

Hello! I just need some help understanding this line of working.

R = 200 * 0.9^x

dR/dx = 200 * (0.9)^x ln 0.9

I fully understand how the 0.9^x is differentiated, but I don't get why the 200 stays the same? Any explanation is much appreciated!
Original post by poppjngcandy
Hello! I just need some help understanding this line of working.

R = 200 * 0.9^x

dR/dx = 200 * (0.9)^x ln 0.9

I fully understand how the 0.9^x is differentiated, but I don't get why the 200 stays the same? Any explanation is much appreciated!

Its a constant multplier so that doesnt change. The derivative of
4x^2
is
8x = 4*(2x)
so this is the same. You could prove both using the product rule or use the basic definition of differentiation.
(edited 6 months ago)
Original post by mqb2766
Its a constant multplier so that doesnt change. The derivative of
4x^2
is
8x = 4*(2x)
so this is the same. You could prove both using the product rule or use the basic definition of differentiation.

thank you