Question : $\left(4 x^3 y-6 x^2 y^2+4 x y^3-y^4\right)$ can be expressed as:
Option 1: $(x+y)^4-x^4$
Option 2: $(x+y)^4-y^4$
Option 3: $(x-y)^4-x^4$
Option 4: $x^4-(x-y)^4$
Correct Answer: $x^4-(x-y)^4$
Solution : $\left(4 x^3 y-6 x^2 y^2+4 x y^3-y^4\right)$ $=2xy^3 + 2xy^3 - 2x^2y^2 - 4x^2y^2 + 4x^3y- y^4 $ $=2xy^3 - 2x^2y^2 - y^4 + 4x^3y + 2xy^3 - 4x^2y^2$ $=-y^2(-2xy + 2x^2 + y^2) + 2xy (2x^2 + y^2 - 2xy)$ $=(2xy - y^2) (2x^2 + y^2 - 2xy)$ $=(x^2 - x^2 - y^2 + 2xy) (x^2 + x^2 + y^2 - 2xy)$ $=[x^2 - (x - y)^2] [x^2 + (x - y)^2]$ $=x^4 - (x - y)^4$ Hence, the correct answer is $x^4 - (x - y)^4$.
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Question : What is $\frac{\left (x^{2}-y^{2} \right)^{3}+\left (y^{2}-z^{2} \right )^{3}+\left (z^{2}-x^{2} \right )^{3}}{\left (x-y \right)^{3}+\left (y-z \right )^{3}+\left (z-x \right)^{3}}?$
Option 1: $\frac{(x+y)(y+z)}{(x+z)}$
Option 2: $(x+y)^3(y+z)^3(z+x)^3$
Option 3: $(x+y)(y+z)(z+x)$
Option 4: $(x+y)(y+z)$
Question : The value of $\frac{(x-y)^3+(y-z)^3+(z-x)^3}{\left(x^2-y^2\right)^3+\left(y^2-z^2\right)^3+\left(z^2-x^2\right)^3}$, where $x \neq y \neq z$, is:
Option 1: $0$
Option 2: $\frac{1}{(x+y+z)}$
Option 3: $\frac{1}{(x+y)(y+z)(z+x)}$
Option 4: $1$
Question : What is the simplified value of: $\frac{1}{8}\left\{\left(x+\frac{1}{y}\right)^2-\left(x-\frac{1}{y}\right)^2\right\}$
Option 1: $\frac{x}{y}$
Option 2: $\frac{2x}{y}$
Option 3: $\frac{x}{2y}$
Option 4: $\frac{4x}{y}$
Question : If $x^2-3 x+1=0$, then the value of $\left(x^4+\frac{1}{x^2}\right) \div\left(x^2+1\right)$ is:
Option 1: 5
Option 2: 6
Option 3: 9
Option 4: 7
Question : If $x^4+y^4=x^2 y^2$, then the value of $x^6+y^6$ is:
Option 1: 2
Option 2: 0
Option 3: 1
Option 4: 3
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