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2 years ago

Just question 7 thanks

Mathematics

1 answer:

ad-work [718]2 years ago

5 0

Let x be the number of boys, the number of girls will be 200-x

Number of boys with blue eyes x/3
Number of girls with blue eyes (200-x)/4
ll blue eyes ==> x/3 + (200-x)/4 = 57
Reduce to same denominator & solve for x
(4x + 600 - 3x)/12 = 681/12
x=81, the total number of boys & girls200-81 119

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b) In this case $u=\sec(2x)$ hence $du=2\tan(2x)\sec(2x)dx$ . We rewrite the integral as $\int 20\tan(2x)\sec^2(2x)dx=\int 10\sec(2x) (2\tan(2x)\sec(2x))dx=\int 10udu=5\frac{u^2}{2}+C=5\sec^2(2x)+C$ .

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