The problem has three parts: (i) Simplify the expression $(2xy^{-2})(4x^{-4}y)$. (ii) Differentiate $y = (3x+1)^3$ with respect to $x$. (iii) Solve the quadratic equation $5x^2 - 11x + 2 = 0$.

AlgebraAlgebraic SimplificationDifferentiationChain RuleQuadratic EquationsQuadratic Formula
2025/5/8

1. Problem Description

The problem has three parts:
(i) Simplify the expression (2xy2)(4x4y)(2xy^{-2})(4x^{-4}y).
(ii) Differentiate y=(3x+1)3y = (3x+1)^3 with respect to xx.
(iii) Solve the quadratic equation 5x211x+2=05x^2 - 11x + 2 = 0.

2. Solution Steps

(i) Simplify (2xy2)(4x4y)(2xy^{-2})(4x^{-4}y).
Multiply the coefficients and add the exponents of like variables.
(2xy2)(4x4y)=(24)(x1+(4))(y2+1)=8x3y1=8x3y (2xy^{-2})(4x^{-4}y) = (2 \cdot 4)(x^{1+(-4)})(y^{-2+1}) = 8x^{-3}y^{-1} = \frac{8}{x^3y}
(ii) Differentiate y=(3x+1)3y = (3x+1)^3 with respect to xx.
We use the chain rule: dydx=dydududx\frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx}. Let u=3x+1u = 3x+1, then y=u3y = u^3.
dydu=3u2 \frac{dy}{du} = 3u^2
dudx=3 \frac{du}{dx} = 3
Therefore,
dydx=3u23=9u2=9(3x+1)2=9(9x2+6x+1)=81x2+54x+9 \frac{dy}{dx} = 3u^2 \cdot 3 = 9u^2 = 9(3x+1)^2 = 9(9x^2 + 6x + 1) = 81x^2 + 54x + 9
(iii) Solve the quadratic equation 5x211x+2=05x^2 - 11x + 2 = 0.
We can use the quadratic formula to solve for xx:
x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
In this case, a=5a = 5, b=11b = -11, and c=2c = 2.
x=(11)±(11)24(5)(2)2(5)=11±1214010=11±8110=11±910 x = \frac{-(-11) \pm \sqrt{(-11)^2 - 4(5)(2)}}{2(5)} = \frac{11 \pm \sqrt{121 - 40}}{10} = \frac{11 \pm \sqrt{81}}{10} = \frac{11 \pm 9}{10}
Thus, we have two possible solutions:
x1=11+910=2010=2 x_1 = \frac{11 + 9}{10} = \frac{20}{10} = 2
x2=11910=210=15 x_2 = \frac{11 - 9}{10} = \frac{2}{10} = \frac{1}{5}

3. Final Answer

(i) 8x3y\frac{8}{x^3y}
(ii) 81x2+54x+981x^2 + 54x + 9
(iii) x=2x=2 or x=15x=\frac{1}{5}