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I have to find the x-intercept of y=cube root(-x+1) +2. I worked it out as follows:

(Important: +2 is not part of the cube root, only -x+1 is under the root)

0=cuberoot(x+1)+2
cuberoot(x+1)=-2
x+1=-8*
x=-9

* I cubed both sides to get rid of the cube root.

When I type it in a graphing calculator it appears that x-intercept is actually 9, not -9.

2007-11-15 07:32:32 · 3 answers · asked by IK 3 in Science & Mathematics Mathematics

3 answers

The original problem was y=cube root(-x+1) +2

but your work (thanks for that!) starts

0=cuberoot(x+1)+2

Your approach is correct; just add that pesky minus sign and you'll get +9.

2007-11-15 07:37:58 · answer #1 · answered by Ron W 7 · 1 0

y=cube root(-x+1) +2 = 0 when
(-x+1)^(1/3) = -2, CUBE both
(-x+1) = -8, so
-x = -8 -1, note signes
x = 9, as it shows in the graph.

2007-11-15 07:40:10 · answer #2 · answered by Anonymous · 0 0

here is your error

you start with y=cube root(-x+1) +2

yet later on you type cuberoot(x+1)+2
what happened to the -x in -x +1 ???

how did it become x +1 ??

2007-11-15 07:38:58 · answer #3 · answered by Anonymous · 0 0

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