3s-4(1+3s)=8+3s

Question

i got a different answer than my teacher and i was wondering which was right. s= -1 or s= -2.

Answer 1

3s-4(1+3s)=8+3s
i got a different answer than my teacher and i was
wondering which was right. s= -1 or s= -2.

How often are teachers right?

3s - 4(1 + 3s) = 8 + 3s
3s - 4 - 12s = 8 + 3s
3s - 4 - 12s - 3s = 8 + 3s - 3s
-4 - 12s = 8
-4 - 12s + 4 = 8 + 4
-12s = 12
-12s / -12 = 12 / -12
s = -1

Check it by plugging the value for s into the equation.

3s - 4(1 + 3s) = 8 + 3s

3(-1) - 4(1 + 3(-1)) = 8 + 3(-1)
-3 - 4(1 - 3) = 8 - 3
-3 - 4(-2) = 5
-3 + 8 = 5
5 = 5

s = -1
Looks like this time your teacher was right.

Comments

Just for fun, try - 2 as the value of s.

3s - 4(1 + 3s) = 8 + 3s
3(-2) - 4(1 + 3(-2)) = 8 + 3(-2)
-6 - 4(1 - 6) = 8 - 6
-6 -4(-5) = 8 - 6
-6 + 20 = 2
14 ≠ 2