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Given the quantity of 3 x squared plus x minus 4, all over x minus 1, what are the domain and range?

Given the quantity of 3 x squared plus x minus 4, all over x minus 1, what are the-example-1
User Hua Zhang
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1 Answer

3 votes

Answer:

4th answer option

Explanation:

the domain is easy : x must not be 1 to avoid 0 in the denominator (and hence a .../0 expression).

that eliminates the 1st and 3rd answer.

for the range :

x = 0 gives us y = -4/-1 = 4

x = 2 gives us y = 10/1 = 10

so, it is very likely that limit for y = 7 for x = 1, which is then the impossible y-value in the range for the impossible x- value.

let's verify with

l'Hopital's Rule

If lim x→a f(x) = 0

and

lim x→a g(x) = 0

then

lim x→a f(x)/g(x) = lim x→a f'(x)/g'(x)

f = 3x² + x - 4

f' = 6x + 1

g = x - 1

g' = 1

f'(x)/g'(x) = (6x + 1)/1 = 6x + 1

for a = 1, therefore x = 1

6×1 + 1 = 7

so, yes, as the limit for x = 1 is y = 7, for the invalid domain value x = 1, the invalid range value is y = 7.

User Birdie
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