Si f(x)=4x+5 cual es el valor de f(_3)?

The general form of the quetion of a circle is ax^2+by^2+cx+dy+e=0 where a=b=0 if the circle has a radius of three units and the center lies on the y axis which set of values of a, b, c, d, and e might correspond to the circle

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?

Which shows the correct substitution of the values a,b and c from the equation 1=-2x+3x^2+1