1. The problem asks to solve or explain the exercises in chapter 8, section 1 (8.1) of the CBSE syllabus. Since the user did not specify a particular question, I will solve the first problem from 8.1, which typically involves linear equations in one variable. 2. A common problem in 8.1 is to solve an equation like $2x + 3 = 7$. 3. The formula or rule used is to isolate the variable $x$ by performing inverse operations on both sides of the equation. 4. Step-by-step solution: 1. Start with the equation: $$2x + 3 = 7$$ 2. Subtract 3 from both sides to isolate the term with $x$: $$2x + 3 - 3 = 7 - 3$$ $$2x = 4$$ 3. Divide both sides by 2 to solve for $x$: $$\frac{\cancel{2}x}{\cancel{2}} = \frac{4}{2}$$ $$x = 2$$ 5. Explanation: We performed inverse operations to keep the equation balanced. Subtracting 3 removes the constant term on the left, and dividing by 2 isolates $x$. 6. Final answer: $$x = 2$$