Answer:
x=-11
y=-1
Step-by-step explanation:
x=4y-7
2x+9y=-31
2(4y-7)+9y=-31
8y-14+9y=-31
17=-31+14
17y=-17
x=4(-1)-7
x = -11, y = -1
solving simultaneously,
2(4y-7) + 9y = -31
17y = 14 - 31
17y = -17
y = -1
back sub, we get:
x = 4(-1)-7
x = -11
so x = -11, y = -1
90
B
2√30
Pythagorean Theorem: a^2 + b^2 = c^2
7^2 + b^2 = 13^2
b^2 = 120
b = 2√30
