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QUESTION TWO: A- (1) the average rate of change of the function y = f(x), when x changes to x + Ax is written as: B- (1) If y = ax², where a is a real number, then dy/dx =. (2) Find the first derivative of the following functions: i− y = 3x²/(x+1)

Mathematics

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Here are the solutions for the problems from the image:

Top Left (4):

  • lim⁡x→0sin⁡3xx\lim_{x \to 0} \frac{\sin 3x}{x}
  1. To evaluate this limit, we use the standard limit lim⁡u→0sin⁡uu=1\lim_{u \to 0} \frac{\sin u}{u} = 1.

    We need to make the argument of the sine function match the denominator. lim⁡x→0sin⁡3xx=lim⁡x→03sin⁡3x3x \lim_{x \to 0} \frac{\sin 3x}{x} = \lim_{x \to 0} \frac{3 \sin 3x}{3x}

  2. Let u=3xu = 3x.

    As x→0x \to 0, u→0u \to 0. 3lim⁡u→0sin⁡uu=3×1 3 \lim_{u \to 0} \frac{\sin u}{u} = 3 \times 1

  3. Calculate the final value.

    $$
    3 \times 1 = \boxed{3}
    $$
    

    Top Right (2):

    • Find the first derivative of the function y=f(x)=x2y = f(x) = x^2, from the first principles.
  4. The definition of the derivative from first principles is

    $$
    f'(x) = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}
    $$
    
  5. Substitute f(x)=x2f(x) = x^2 into the formula.

    $$
    f(x+h) = (x+h)^2 = x^2 + 2xh + h^2
    $$
    
  6. Calculate f(x+h)−f(x)f(x+h) - f(x).

    $$
    f(x+h) - f(x) = (x^2 + 2xh + h^2) - x^2 = 2xh + h^2
    $$
    
  7. Substitute this back into the limit expression.

    $$
    f'(x) = \lim_{h \to 0} \frac{2xh + h^2}{h}
    $$
    
  8. Factor out hh from the numerator and simplify.

    $$
    f'(x) = \lim_{h \to 0} \frac{h(2x + h)}{h} = \lim_{h \to 0} (2x + h)
    $$
    
  9. Evaluate the limit as h→0h \to 0.

    $$
    f'(x) = 2x + 0 = \boxed{2x}
    $$
    

    QUESTION TWO:

    A-(1) The average rate of change of the function y=f(x)y = f(x), when xx changes to x+Δxx + \Delta x is written as:
    The average rate of change is defined as the change in yy divided by the change in xx.

    ΔyΔx=f(x+Δx)−f(x)Δx\frac{\Delta y}{\Delta x} = \boxed{\frac{f(x+\Delta x) - f(x)}{\Delta x}}

    B-(1) If y=ax2y = ax^2, where aa is a real number, then dydx=_\frac{dy}{dx} = \_

  10. Apply the power rule for differentiation, which states that ddx(cxn)=cnxn−1\frac{d}{dx}(cx^n) = cnx^{n-1}.

    Here, c=ac=a and n=2n=2.

    dydx=a⋅2x2−1\frac{dy}{dx} = a \cdot 2x^{2-1}
  11. Simplify the expression.

    dydx=2ax\frac{dy}{dx} = \boxed{2ax}

    B-(2) Find the first derivative of the following functions:

    • i- y=3x2x+1y = \frac{3x^2}{x+1}
  12. Use the quotient rule for differentiation, which states that if y=uvy = \frac{u}{v}, then dydx=u′v−uv′v2\frac{dy}{dx} = \frac{u'v - uv'}{v^2}.

    Let $u = 3x^2$, so $u' = \frac{d}{dx}(3x^2) = 6x$.  
    Let $v = x+1$, so $v' = \frac{d}{dx}(x+1) = 1$.
    
  13. Substitute $u, u', v, v'$ into the quotient rule formula.

    $$
    \frac{dy}{dx} = \frac{(6x)(x+1) - (3x^2)(1)}{(x+1)^2}
    $$
    
  14. Expand the numerator.

    $$
    \frac{dy}{dx} = \frac{6x^2 + 6x - 3x^2}{(x+1)^2}
    $$
    
  15. Combine like terms in the numerator.

    $$
    \frac{dy}{dx} = \boxed{\frac{3x^2 + 6x}{(x+1)^2}}
    $$
    (Alternatively, you can factor the numerator: $\frac{3x(x+2)}{(x+1)^2}$)
    
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