Solve
$ \dfrac{2}{{x + 1}} + \dfrac{3}{{2\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}},\,\,x \ne 0, - 1,2 $
Answer
628.5k+ views
Hint: For this type of problems we first simplify both side by taking L.C.M. of fraction terms present on both side and then cross multiplying to form either a linear equation or a quadratic equation and then solving an equation so obtained to find value of ‘x’ or require solution of given problem.
Complete step-by-step answer:
Given equation is $ \dfrac{2}{{x + 1}} + \dfrac{3}{{2\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}},\,\,x \ne 0, - 1,2 $
To solve the above equation. We first take L.C.M. of left hand side term and then cross multiplying to form an equation.
\[
\dfrac{{4\left( {x - 2} \right) + 3\left( {x + 1} \right)}}{{2\left( {x + 1} \right)\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}} \\
\Rightarrow \dfrac{{4x - 8 + 3x + 3}}{{2\left( {x + 1} \right)\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}} \\
\Rightarrow \dfrac{{7x - 5}}{{2\left( {x + 1} \right)\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}} \\
\]
Cross multiplying above. We have,
$
5x\left( {7x - 5} \right) = 23\left\{ {2\left( {x + 1} \right)\left( {x - 2} \right)} \right\} \\
\Rightarrow 35{x^2} - 25x = 46\left( {{x^2} - 2x + x - 2} \right) \\
\Rightarrow 35{x^2} - 25x = 46\left( {{x^2} - x - 2} \right) \\
\Rightarrow 35{x^2} - 25x = 46{x^2} - 46x - 92 \\
\Rightarrow 35{x^2} - 25x - 46{x^2} + 46x + 92 = 0 \\
\Rightarrow - 11{x^2} + 21x + 92 = 0 \\
or \\
11{x^2} - 21x - 92 = 0 \;
$
Now, solving the above equation by quadratic formula method.
Comparing the above formed equation with standard quadratic equation $ a{x^2} + bx + c = 0 $ . We have,
$ a = 11,\,\,b = - 21\,\,and\,\,c = - 92 $
Calculating discriminant of quadratic. Given as:
$ D = {b^2} - 4ac $
Substituting values of a, b and c in above.
$
D = {\left( { - 21} \right)^2} - 4\left( {11} \right)\left( { - 92} \right) \\
\Rightarrow D = 441 + 4048 \\
\Rightarrow D = 4489 \;
$
As, $ D > 0 $ Therefore, roots of a quadratic equations are real but unequal and given as:
$ \alpha = \dfrac{{ - b + \sqrt D }}{{2a}},\,\,\beta = \dfrac{{ - b - \sqrt D }}{{2a}} $
Substituting values in above. We have,
$
\alpha = \dfrac{{ - \left( { - 21} \right) + \sqrt {4489} }}{{2(11)}},\,\,\beta = \dfrac{{ - \left( { - 21} \right) - \sqrt {4489} }}{{2(11)}} \\
\Rightarrow \alpha = \dfrac{{21 + 67}}{{22}},\,\,\beta = \dfrac{{21 - 67}}{{22}} \\
\Rightarrow \alpha = \dfrac{{88}}{{22}},\,\,\beta = \dfrac{{ - 46}}{{22}} \\
\Rightarrow \alpha = 4,\,\,\beta = - \dfrac{{23}}{{11}} \\
$
Or we can say that roots of quadratic equation are $ x = 4\,\,and\,\,x = - \dfrac{{23}}{{11}} $
Therefore, from above we can see that solution of given equation $ \dfrac{2}{{x + 1}} + \dfrac{3}{{2\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}},\,\,x \ne 0, - 1,2 $ are $ x = 4\,\,and\,\,x = - \dfrac{{23}}{{11}} $
So, the correct answer is “$ x = 4\,\,and\,\,x = - \dfrac{{23}}{{11}} $ ”.
Note: In this type of problems one can solve by first shifting all terms to the left side and then simplifying it by taking LCM and solving the equation so formed. If the equation so form will be linear then one directly finds its solution but if it will be a quadratic then there different ways to solve a quadratic equation like middle term splitting method, completing square method and quadratic formula method. One can apply either one as the answer will be the same in any case.
Complete step-by-step answer:
Given equation is $ \dfrac{2}{{x + 1}} + \dfrac{3}{{2\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}},\,\,x \ne 0, - 1,2 $
To solve the above equation. We first take L.C.M. of left hand side term and then cross multiplying to form an equation.
\[
\dfrac{{4\left( {x - 2} \right) + 3\left( {x + 1} \right)}}{{2\left( {x + 1} \right)\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}} \\
\Rightarrow \dfrac{{4x - 8 + 3x + 3}}{{2\left( {x + 1} \right)\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}} \\
\Rightarrow \dfrac{{7x - 5}}{{2\left( {x + 1} \right)\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}} \\
\]
Cross multiplying above. We have,
$
5x\left( {7x - 5} \right) = 23\left\{ {2\left( {x + 1} \right)\left( {x - 2} \right)} \right\} \\
\Rightarrow 35{x^2} - 25x = 46\left( {{x^2} - 2x + x - 2} \right) \\
\Rightarrow 35{x^2} - 25x = 46\left( {{x^2} - x - 2} \right) \\
\Rightarrow 35{x^2} - 25x = 46{x^2} - 46x - 92 \\
\Rightarrow 35{x^2} - 25x - 46{x^2} + 46x + 92 = 0 \\
\Rightarrow - 11{x^2} + 21x + 92 = 0 \\
or \\
11{x^2} - 21x - 92 = 0 \;
$
Now, solving the above equation by quadratic formula method.
Comparing the above formed equation with standard quadratic equation $ a{x^2} + bx + c = 0 $ . We have,
$ a = 11,\,\,b = - 21\,\,and\,\,c = - 92 $
Calculating discriminant of quadratic. Given as:
$ D = {b^2} - 4ac $
Substituting values of a, b and c in above.
$
D = {\left( { - 21} \right)^2} - 4\left( {11} \right)\left( { - 92} \right) \\
\Rightarrow D = 441 + 4048 \\
\Rightarrow D = 4489 \;
$
As, $ D > 0 $ Therefore, roots of a quadratic equations are real but unequal and given as:
$ \alpha = \dfrac{{ - b + \sqrt D }}{{2a}},\,\,\beta = \dfrac{{ - b - \sqrt D }}{{2a}} $
Substituting values in above. We have,
$
\alpha = \dfrac{{ - \left( { - 21} \right) + \sqrt {4489} }}{{2(11)}},\,\,\beta = \dfrac{{ - \left( { - 21} \right) - \sqrt {4489} }}{{2(11)}} \\
\Rightarrow \alpha = \dfrac{{21 + 67}}{{22}},\,\,\beta = \dfrac{{21 - 67}}{{22}} \\
\Rightarrow \alpha = \dfrac{{88}}{{22}},\,\,\beta = \dfrac{{ - 46}}{{22}} \\
\Rightarrow \alpha = 4,\,\,\beta = - \dfrac{{23}}{{11}} \\
$
Or we can say that roots of quadratic equation are $ x = 4\,\,and\,\,x = - \dfrac{{23}}{{11}} $
Therefore, from above we can see that solution of given equation $ \dfrac{2}{{x + 1}} + \dfrac{3}{{2\left( {x - 2} \right)}} = \dfrac{{23}}{{5x}},\,\,x \ne 0, - 1,2 $ are $ x = 4\,\,and\,\,x = - \dfrac{{23}}{{11}} $
So, the correct answer is “$ x = 4\,\,and\,\,x = - \dfrac{{23}}{{11}} $ ”.
Note: In this type of problems one can solve by first shifting all terms to the left side and then simplifying it by taking LCM and solving the equation so formed. If the equation so form will be linear then one directly finds its solution but if it will be a quadratic then there different ways to solve a quadratic equation like middle term splitting method, completing square method and quadratic formula method. One can apply either one as the answer will be the same in any case.
Recently Updated Pages
Find the greatest six digit number that is exactly class 8 maths CBSE

What is the time difference between India and Cana class 8 social science CBSE

Compare LPG and wood as fuels class 8 chemistry CBSE

In Indian rupees 1 trillion is equal to how many c class 8 maths CBSE

30 opposite words in English from a to z class 8 english CBSE

How many cubic feet equals to 1 unit sand class 8 maths CBSE

Trending doubts
What is BLO What is the full form of BLO class 8 social science CBSE

Citizens of India can vote at the age of A 18 years class 8 social science CBSE

Full form of STD, ISD and PCO

One cusec is equal to how many liters class 8 maths CBSE

Who commanded the Hector the first British trading class 8 social science CBSE

What are the methods of reducing friction. Explain

