this is system of equations
2x + 5y = -1 times this one by 5 to make the y's opposite
-10x -25y = 5
10x - 25y = -5 (this is it times by 5, now add them)
__________
0 + 0 = 0
now since everything cancels and both sides are equal it has infinite solutions beaus they are actually the same line.
2 is less than is greater than or equal to 4 and less than or equal to 9.
A² + b² = c²
a² = c² - b²
a² = 9² - 6²
a² = 81 - 36
a² = 45
a = √45
a ≈ 6.7082
a = 6.7