Answer:
12
Step-by-step explanation:
a² + b² = c²
a² + 9² = 15²
a² + 81 = 225
a² = 225 - 81
a² = 144

a = 12
Step-by-step explanation:
x2+2xy+y2-1,y2-x2+2y+1,x2-y2+2x+1
The coefficient (letter chosen) that is used does not matter as it is only to show that it is an unknown variable, if you have more than one variable you need more than one type of coefficient (use different letters for different ones you dont know).
Answer:

Step-by-step explanation:
To simplify the fraction find the GCF (greatest common factor). The GCF is the largest number that is a factor of both the numerator and denominator. Both 24 and 56 have a factor of 8, this is the GCF. Divide both numbers by 8 to get the final answer of 3/7.