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3 years ago

Please help me. I need how to do the problem too

Mathematics

1 answer:

MatroZZZ [7]3 years ago

5 0

Answer: Choice A. (8, 4)

==========================================================

Explanation:

Because x = 2y, we can replace every copy of x with 2y

Let's do so in the second equation

3x - 4y = 8

3(x) - 4y = 8

3(2y) - 4y = 8 .... x replaced with 2y; now let's isolate y

6y - 4y = 8

2y = 8

y = 8/2 ..... divide both sides by 2

y = 4

Use this y value to find x

x = 2y

x = 2*4

x = 8

So we have x = 8 and y = 4 pair together to get the answer (x,y) = (8, 4) which is choice A.

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Step-by-step explanation:

(a)

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$\frac{b}{a}=\frac{\sinB}{\sin A}
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Again consider,

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Now find $\frac{dB}{dA}$

Differentiate implicitly the function $\sin{B}=\sqrt{\frac{3}{2}}\sin{A}$ with respect to A to get,

$\cos {B}.\frac{dB}{dA}=\sqrt{\frac{3}{2}}\cos A\\\\\frac{dB}{dA}=\sqrt{\frac{3}{2}}.\frac{\cos A}{\cos B}$

When $A=\frac{\pi}{4},B=\frac{\pi}{3}$ , the value of $\frac{dB}{dA}$ is,

$\frac{dB}{dA}=\sqrt{\frac{3}{2}}.\frac{\cos {\frac{\pi}{4}}}{\cos {\frac{\pi}{3}}}\\\\=\sqrt{\frac{3}{2}}.\frac{\frac{1}{\sqrt{2}}}{\frac{1}{2}}\\\\=\sqrt{3}$

In general, the linear approximation at x= a is,

$f(x)=f'(x).(x-a)+f(a)$

Here the function $f(A)=B=\sin^{-1}[\sqrt{\frac{3}{2}}\sin{A}]$

At $A=\frac{\pi}{4}$

$f(\frac{\pi}{4})=B=\sin^{-1}[\sqrt{\frac{3}{2}}\sin{\frac{\pi}{4}}]\\\\=\sin^{-1}[\sqrt{\frac{3}{2}}.\frac{1}{\sqrt{2}}]\\\\\=\sin^{-1}(\frac{\sqrt{2}}{2})\\\\=\frac{\pi}{3}$