👉 Try now NerdPal! Our new math app on iOS and Android

Find the limit $\lim_{x\to3}\left(\frac{2x^3-5x^2-2x-3}{4x^3-13x^2+4x-3}\right)$

Step-by-step Solution

Go!
Math mode
Text mode
Go!
1
2
3
4
5
6
7
8
9
0
a
b
c
d
f
g
m
n
u
v
w
x
y
z
.
(◻)
+
-
×
◻/◻
/
÷
2

e
π
ln
log
log
lim
d/dx
Dx
|◻|
θ
=
>
<
>=
<=
sin
cos
tan
cot
sec
csc

asin
acos
atan
acot
asec
acsc

sinh
cosh
tanh
coth
sech
csch

asinh
acosh
atanh
acoth
asech
acsch

Final Answer

$\frac{11}{17}$
Got another answer? Verify it here!

Step-by-step Solution

Specify the solving method

1

We can factor the polynomial $4x^3-13x^2+4x-3$ using the rational root theorem, which guarantees that for a polynomial of the form $a_nx^n+a_{n-1}x^{n-1}+\dots+a_0$ there is a rational root of the form $\pm\frac{p}{q}$, where $p$ belongs to the divisors of the constant term $a_0$, and $q$ belongs to the divisors of the leading coefficient $a_n$. List all divisors $p$ of the constant term $a_0$, which equals $-3$

$1, 3$
2

Next, list all divisors of the leading coefficient $a_n$, which equals $4$

$1, 2, 4$
3

The possible roots $\pm\frac{p}{q}$ of the polynomial $4x^3-13x^2+4x-3$ will then be

$\pm\frac{1}{2},\:\pm\frac{1}{4},\:\pm1,\:\pm\frac{3}{2},\:\pm\frac{3}{4},\:\pm3$
4

Trying all possible roots, we found that $3$ is a root of the polynomial. When we evaluate it in the polynomial, it gives us $0$ as a result

$4\cdot 3^3-13\cdot 3^2+4\cdot 3-3=0$
5

Now, divide the polynomial by the root we found $\left(x-3\right)$ using synthetic division (Ruffini's rule). First, write the coefficients of the terms of the numerator in descending order. Then, take the first coefficient $4$ and multiply by the factor $3$. Add the result to the second coefficient and then multiply this by $3$ and so on

$\left|\begin{array}{c}4 & -13 & 4 & -3 \\ & 12 & -3 & 3 \\ 4 & -1 & 1 & 0\end{array}\right|3$
6

In the last row of the division appear the new coefficients, with remainder equals zero. Now, rewrite the polynomial (a degree less) with the new coefficients, and multiplied by the factor $\left(x-3\right)$

$\lim_{x\to3}\left(\frac{2x^3-5x^2-2x-3}{\left(4x^{2}-x+1\right)\left(x-3\right)}\right)$
7

We can factor the polynomial $2x^3-5x^2-2x-3$ using the rational root theorem, which guarantees that for a polynomial of the form $a_nx^n+a_{n-1}x^{n-1}+\dots+a_0$ there is a rational root of the form $\pm\frac{p}{q}$, where $p$ belongs to the divisors of the constant term $a_0$, and $q$ belongs to the divisors of the leading coefficient $a_n$. List all divisors $p$ of the constant term $a_0$, which equals $-3$

$1, 3$
8

Next, list all divisors of the leading coefficient $a_n$, which equals $2$

$1, 2$
9

The possible roots $\pm\frac{p}{q}$ of the polynomial $2x^3-5x^2-2x-3$ will then be

$\pm\frac{1}{2},\:\pm1,\:\pm\frac{3}{2},\:\pm3$
10

Trying all possible roots, we found that $3$ is a root of the polynomial. When we evaluate it in the polynomial, it gives us $0$ as a result

$2\cdot 3^3-5\cdot 3^2-2\cdot 3-3=0$
11

Now, divide the polynomial by the root we found $\left(x-3\right)$ using synthetic division (Ruffini's rule). First, write the coefficients of the terms of the numerator in descending order. Then, take the first coefficient $2$ and multiply by the factor $3$. Add the result to the second coefficient and then multiply this by $3$ and so on

$\left|\begin{array}{c}2 & -5 & -2 & -3 \\ & 6 & 3 & 3 \\ 2 & 1 & 1 & 0\end{array}\right|3$
12

In the last row of the division appear the new coefficients, with remainder equals zero. Now, rewrite the polynomial (a degree less) with the new coefficients, and multiplied by the factor $\left(x-3\right)$

$\lim_{x\to3}\left(\frac{\left(2x^{2}+x+1\right)\left(x-3\right)}{\left(4x^{2}-x+1\right)\left(x-3\right)}\right)$
13

Simplify the fraction $\frac{\left(2x^{2}+x+1\right)\left(x-3\right)}{\left(4x^{2}-x+1\right)\left(x-3\right)}$ by $x-3$

$\lim_{x\to3}\left(\frac{2x^{2}+x+1}{4x^{2}-x+1}\right)$
14

Evaluate the limit $\lim_{x\to3}\left(\frac{2x^{2}+x+1}{4x^{2}-x+1}\right)$ by replacing all occurrences of $x$ by $3$

$\frac{2\cdot 3^{2}+3+1}{4\cdot 3^{2}-3+1}$
15

Subtract the values $1$ and $-3$

$\frac{2\cdot 3^{2}+3+1}{-2+4\cdot 3^{2}}$
16

Add the values $3$ and $1$

$\frac{4+2\cdot 3^{2}}{-2+4\cdot 3^{2}}$
17

Calculate the power $3^{2}$

$\frac{4+2\cdot 3^{2}}{-2+4\cdot 9}$
18

Multiply $4$ times $9$

$\frac{4+2\cdot 3^{2}}{-2+36}$
19

Subtract the values $36$ and $-2$

$\frac{4+2\cdot 3^{2}}{34}$
20

Calculate the power $3^{2}$

$\frac{4+2\cdot 9}{34}$
21

Multiply $2$ times $9$

$\frac{4+18}{34}$
22

Add the values $4$ and $18$

$\frac{22}{34}$
23

Divide $22$ by $34$

$\frac{11}{17}$

Final Answer

$\frac{11}{17}$

Exact Numeric Answer

$0.6471$

Explore different ways to solve this problem

Solving a math problem using different methods is important because it enhances understanding, encourages critical thinking, allows for multiple solutions, and develops problem-solving strategies. Read more

Limits by Direct SubstitutionLimits by L'Hôpital's ruleLimits by FactoringLimits by Rationalizing

Give us your feedback!

Function Plot

Plotting: $\frac{2x^3-5x^2-2x-3}{4x^3-13x^2+4x-3}$

SnapXam A2
Answer Assistant

beta
Got a different answer? Verify it!

Go!
1
2
3
4
5
6
7
8
9
0
a
b
c
d
f
g
m
n
u
v
w
x
y
z
.
(◻)
+
-
×
◻/◻
/
÷
2

e
π
ln
log
log
lim
d/dx
Dx
|◻|
θ
=
>
<
>=
<=
sin
cos
tan
cot
sec
csc

asin
acos
atan
acot
asec
acsc

sinh
cosh
tanh
coth
sech
csch

asinh
acosh
atanh
acoth
asech
acsch

How to improve your answer:

Main Topic: Limits by Direct Substitution

Find limits of functions at a specific point by directly plugging the value into the function.

Your Math & Physics Tutor. Powered by AI

Available 24/7, 365.

Unlimited step-by-step math solutions. No ads.

Includes multiple solving methods.

Support for more than 100 math topics.

Premium access on our iOS and Android apps as well.

20% discount on online tutoring.

Choose your subscription plan:
Have a promo code?
Pay $39.97 USD securely with your payment method.
Please hold while your payment is being processed.
Create an Account