Bart has two choices to make a long distance phone call. His two choices are:10-10-220 and AT&T. Using 10-10220, the cost is 99¢ for the first twenty minutes, and 7¢ for each additional minute. AT&T just charges 6¢ for each minute. After how many total minutes will it be less expensive to use AT&T? Assume the call is at least 20 minutes.

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.

step-by-step explanation:

1. a^4+8a^3+24a^2+32a+16

2.y^8+8y^7+28y^6+56y^5+70y^4+56y^3+28y^2+8y+1

3.x^6-3x^4y^2+3x^2y^4-y^6