Some students simplify
2x^2 - 32 / x - 4
as
2x - 8
Choose values of x to show this is not true. Then simplify it correctly.
Thanks for the help.
2007-08-30 06:24:18 · 5 answers · asked by Nerds Rule! 6 in Science & Mathematics ➔ Mathematics
I think you probably mean that some students simplify
2x^2 - 32 / x - 4
as
2x + 8
Because, as you can see you can factor the top:
2(x^2 - 16)/(x-4) = 2(x-4)(x+4)/(x-4) = 2(x+4) = 2x + 8.
However, this is not true at x=4.
The reason is that at x=4 you have 0/0 which is a discontinuity!
2007-08-30 06:37:51 · answer #1 · answered by sharky.mark 4 · 1⤊ 0⤋
You want to choose a value for x that would make the two expressions unequal
like 10
2(10)-8=?
2(10^2)-32/10-4=?
to simplify you need to factor 2x^2-32
(2x+?)(x-?)
2007-08-30 06:37:45 · answer #2 · answered by Allen N 2 · 0⤊ 0⤋
first off x = 4 is not defined but try x =0
gets 2x^2 - 32 / x - 4 gives -32/-4 = 8 but 2x - 8 gives
-8
2(X^2 - 16) / x - 4 = 2(x-4)(x+4)/(x-4) = 2(x+4) = 2x + 8
2007-08-30 06:37:35 · answer #3 · answered by timemccormick 3 · 0⤊ 0⤋
2(x² -16)/(x-4) = 2 (x+4)(x-4)/(x-4) = 2(x+4) = 2x +8 and this ios the correct answer
2007-08-30 06:35:53 · answer #4 · answered by mramahmedmram 3 · 0⤊ 0⤋
(2x² - 32)/(x - 4)
2(x² - 16)/(x - 4)
2(x - 4)(x + 4)/(x - 4)
2(x + 4)
2007-08-30 06:32:43 · answer #5 · answered by gebobs 6 · 0⤊ 0⤋