if 7-x/5x+1=3, then what is the value of x+1/x-1?

Correct Answer is : −53-5/3−35

Correct Answer is : −53-5/3−35

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CTET Paper II (Mathematics and Science) 22 Dec 2021 Solved Paper

Question : 40 of 150

Marks: +1, -0

\frac{7-x}{5x+1}=3

\frac{x+1}{x-1}

Solution:

Concept:

Use cross-multiplication to solve for

x

, then substitute into the required expression.

Explanation:

Start with

\frac{7-x}{5x+1}=3

Multiply both sides by

5x+1

7-x = 3(5x+1)

Expand:

7-x = 15x+3

Bring

x

terms to one side:

7-3 = 15x + x

→

4 = 16x

x = \frac{4}{16} = \frac{1}{4}

Now compute

\frac{x+1}{x-1}

with

x=\frac{1}{4}

\frac{\frac{1}{4}+1}{\frac{1}{4}-1} = \frac{\frac{5}{4}}{-\frac{3}{4}} = \frac{5}{4} \times \left(-\frac{4}{3}\right) = -\frac{5}{3}.

Answer:

-\frac{5}{3}

; Option A.

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