It is given that y=2x−1x+2y = \frac{2x-1}{\sqrt{x+2}} for x>qx > q.

  1. (a)

    State the value of qq.

  2. (b)

    Find dydx\dfrac{dy}{dx}.

  3. (c)

    State whether y=2x−1x+2y = \dfrac{2x-1}{\sqrt{x+2}} is an increasing or decreasing function.

    Explain your answer clearly.

Work through it with AI →

It won't just hand you the answer — it asks where you're stuck.How the checker works

Worked solution

6(a)

1. Determine the condition for the function to be defined

For y=2x−1x+2y = \frac{2x-1}{\sqrt{x+2}} to be defined and real, the expression inside the square root in the denominator must be strictly positive.
x+2>0x + 2 > 0
x>−2x > -2

Answer

q=−2q = -2

6(b)

1. Apply the quotient rule to differentiate the function

Let u=2x−1u = 2x - 1 and v=(x+2)12v = (x+2)^{\frac{1}{2}}.
dudx=2\frac{du}{dx} = 2
dvdx=12(x+2)−12\frac{dv}{dx} = \frac{1}{2}(x+2)^{-\frac{1}{2}}

dydx=vdudx−udvdxv2\frac{dy}{dx} = \frac{v \frac{du}{dx} - u \frac{dv}{dx}}{v^2}
dydx=2(x+2)12−(2x−1)[12(x+2)−12]x+2\frac{dy}{dx} = \frac{2(x+2)^{\frac{1}{2}} - (2x-1)\left[\frac{1}{2}(x+2)^{-\frac{1}{2}}\right]}{x+2}

2. Simplify the derivative

Multiply the numerator and the denominator by (x+2)12(x+2)^{\frac{1}{2}} to eliminate the negative exponent:
dydx=2(x+2)−12(2x−1)(x+2)(x+2)12\frac{dy}{dx} = \frac{2(x+2) - \frac{1}{2}(2x-1)}{(x+2)(x+2)^{\frac{1}{2}}}
dydx=2x+4−x+12(x+2)32\frac{dy}{dx} = \frac{2x + 4 - x + \frac{1}{2}}{(x+2)^{\frac{3}{2}}}
dydx=x+4.5(x+2)32\frac{dy}{dx} = \frac{x + 4.5}{(x+2)^{\frac{3}{2}}}
dydx=2x+92(x+2)32\frac{dy}{dx} = \frac{2x+9}{2(x+2)^{\frac{3}{2}}}

Answer

2x+92(x+2)32\frac{2x+9}{2(x+2)^{\frac{3}{2}}}

6(c)

1. Recall the derivative from part (b) and analyse its sign for the given domain

From part (b), dydx=2x+92(x+2)32\frac{dy}{dx} = \frac{2x+9}{2(x+2)^{\frac{3}{2}}}.
For x>−2x > -2, x+2>0x + 2 > 0, so the denominator 2(x+2)32>02(x+2)^{\frac{3}{2}} > 0.
Also, 2x+9>2(−2)+9=5>02x + 9 > 2(-2) + 9 = 5 > 0, so the numerator is positive.

2. Conclude whether the function is increasing or decreasing

Since dydx>0\frac{dy}{dx} > 0 for all x>−2x > -2, yy is an increasing function.

Answer

Increasing function, since dydx>0\frac{dy}{dx} > 0 for all x>−2x > -2.

AI analysis — may contain mistakes.

Worked this one out on paper? Snap your steps and Gigle's AI math checker will circle the step where it went wrong.

More questions on this topic

  1. 1Answer all questions. Given that a=b2+4ac2aa = \sqrt{\frac{b^2+4ac}{2a}}, find the values of bb when a=4a = 4 and c=−1c = -1. Answ…
  2. 2The triangle ABC is such that its area is 16+7102 cm2\dfrac{16 + 7\sqrt{10}}{2}\ \text{cm}^2, the length of AB is (32+5) cm(3\sqrt{2} + \sqrt{5})\ \text{cm}…
  3. 3Find the coordinates of the points of intersection of the curve x+3=2xyx + 3 = 2xy and the curve y=2xy = \frac{2}{\sqrt{x}}.
  4. 4It is given that 2x×32(2x)8x+1=9(52x)−52x+15x−5x−1\frac{2^x \times 32(2^x)}{8^{x+1}} = \frac{9(5^{2x}) - 5^{2x+1}}{5^x - 5^{x-1}}. Evaluate 10x10^x with…
  5. 5The diagram shows part of the curve y=3x+4y = \sqrt{3x + 4}. The line ABAB is tangent to the curve at AA. The points BB an…