Let mathrm{a}=max _{x ∈ R}left{8^{2 sin 3 x} · 4^{4 cos 3 x}right} and β=min

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4-2.Quadratic Equations and Inequations

hard

Let $\mathrm{a}=\max _{x \in R}\left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$ and $\beta=\min _{x \in R}\left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$

If $8 x^{2}+b x+c=0$ is a quadratic equation whose roots are $\alpha^{1 / 5}$ and $\beta^{1 / 5}$, then the value of $c-b$ is equal to:

$43$

$42$

$50$

$47$

(JEE MAIN-2021)

Solution

$\alpha=\max \left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$

$=\max \left\{2^{6 \sin 3 x} \cdot 2^{8 \cos 3 x}\right\}$

$=\max \left\{2^{6 \sin 3 x+8 \cos 3 x}\right\}$

and $\beta=\min \left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}=\min \left\{2^{6 \sin 3 x+8 \cos 3 x}\right\}$

Now range of $6 \sin 3 x+8 \cos 3 x$

$=\left[-\sqrt{6^{2}+8^{2}},+\sqrt{6^{2}+8^{2}}\right]=[-10,10]$

$\alpha=2^{10} \,\&\, \beta=2^{-10}$

$\text { So, } \alpha^{1 / 5}=2^{2}=4$

$\Rightarrow \beta^{1 / 5}=2^{-2}=1 / 4$

$\text { quadratic } 8 x^{2}+b x+c=0, c-b=$

$8 \times[\text { (product of roots })+(\text { sum of roots })]$

$=8 \times\left[4 \times \frac{1}{4}+4+\frac{1}{4}\right]=8 \times\left[\frac{21}{4}\right]=42$

Standard 11

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hard

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hard

(JEE MAIN-2023)

Let $\mathrm{a}=\max _{x \in R}\left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$ and $\beta=\min _{x \in R}\left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$ If $8 x^{2}+b x+c=0$ is a quadratic equation whose roots are $\alpha^{1 / 5}$ and $\beta^{1 / 5}$, then the value of $c-b$ is equal to:

Solution

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Let $\mathrm{a}=\max _{x \in R}\left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$ and $\beta=\min _{x \in R}\left\{8^{2 \sin 3 x} \cdot 4^{4 \cos 3 x}\right\}$

If $8 x^{2}+b x+c=0$ is a quadratic equation whose roots are $\alpha^{1 / 5}$ and $\beta^{1 / 5}$, then the value of $c-b$ is equal to:

Two distinct polynomials $f(x)$ and $g(x)$ are defined as follows:

$f(x)=x^2+a x+2 ; g(x)=x^2+2 x+a$.If the equations $f(x)=0$ and $g(x)=0$ have a common root, then the sum of the roots of the equation $f(x)+g(x)=0$ is