Answer:
Variant c
Step-by-step explanation:
c²=4*9
c=6
You can apply phyphagor
b²=6²+9²=36+81=117

D. X cubed
E. X to the negative 3
7x+5y=-24 (1)
4x+y=42 (2)
multiply equation (2) by 5 to get
20x+5y=210 (3)
then calculate (3)-(2) which gives you
13x=234 hence x=18
then substitute for x in either equation to get y=-30
6a+12=2(3a-8)
6a+12=6a-16
-12. -12
6a=6a-4
-6a -6a
0=-4
no solution because the equation is false.