Find all values of x such that 2x/(x + 2) = -8/(x + 4).
If you find more than one value, then list your solutions, separated by commas.
+2197
Find all values of x such that 2x/(x + 2) = -8/(x + 4).
2x – 8
–––––– = ––––––
x + 2 x + 4
cross multiply to obtain (2x)(x + 4) = (– 8)(x + 2)
2x2 + 8x = – 8x – 16
2x2 + 16x + 16 = 0
x2 + 8x + 8 = 0
can't factor – b + sqrt(b2 – 4ac)
have to use quadratic formula x = ––––––––––––––––
2a
– 8 + sqrt(64 – 32)
x = ––––––––––––––––
2
– 8 + sqrt(32) – 8 + 4 • sqrt(2)
x = –––––––––––– = ––––––––––––––
2 2
x = – 4 + 2 • sqrt(2)
x = – 1.17157
x = – 6.82843
.
