Explicação passo-a-passo:

a)x+6=11

x=11-6=5

b)y+7=6

y=6-7=-1

c)4x-8=2x+6

4x-2x=6+8

2x=14

x=14/2=7

d)5x-3=2x-9

5x-2x=-9+3

3x=-6

x=-6/3=-2

e)5x=25

x=25/5=5

f)-7x=49

x=49/-7

x=-7

g)x²=4

x=√4=2

h)x²=36

x=√36=6