Understanding this proof for the proposition "for all integers a, gcd(9a+4, 2a+1) = 1.

proof: gcd(9a+4, 2a+1) = gcd(2a+1, a) = gcd(a, 1). since gcd(a, 1)=1, gcd(9a+4, 2a+1) =1.

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

Someone answer asap for ! a discount store’s prices are 25% lower than department store prices. the function c(x) = 0.75x can be used to determine the cost c, in dollars, of an item, where x is the department store price, in dollars. if the item has not sold in one month, the discount store takes an additional 20% off the discounted price and an additional $5 off the total purchase. the function d(y) = 0.80y - 5 can be used to find d, the cost, in dollars, of an item that has not been sold for a month, where y is the discount store price, in dollars. create a function d(c(x)) that represents the final price of an item when a costumer buys an item that has been in the discount store for a month. d(c(x)) =

Astudent has created the give circuit diagram. it consists of a battery, a resistor, and a light bulb. in one minute, 1.2c of charge flows through the resistor. how much charge flows through the light bulb in one minute?