#Numerical estimation for an integral, without a calculator

17 messages · Page 1 of 1 (latest)

placid gulch
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This is an MCQ question where one needs to solve it, without a calculator, within 3 minutes. I know Simpson's rule, trapezoidal rule, etc. But it may need a different clever way without actually evaluating numerically.

gritty epochBOT
placid gulch
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<@&286206848099549185>

prime fog
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the integrand is (very) approximately 1+x^2, so I(a,b) = (b + (b^3)/3) - (a + (a^3)/3) is a reasonable approximation

uncut heraldBOT
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Unique

I would agree with thar only when $x \le 1$.

Can you explain more why would you neglect other terms since we have values of x higher than 1?
honest holly
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It's a different kind of approximation

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x^3 + x is not too far from x^2 when x^4 is around

placid gulch
placid gulch
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<@&286206848099549185>

honest holly
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Try plugging in x= 2, then 3, then 4, then 5 into the integrand and see what the numbers look like

placid gulch
uncut heraldBOT
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Unique

honest holly
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the integrand is (very) approximately 1+x^2, so I(a,b) = (b + (b^3)/3) - (a + (a^3)/3) is a reasonable approximation

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What was wrong with this?

placid gulch
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That I do not know how we got that approximation

honest holly
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1 + x + x^2 + x^3 + x^4 is pretty close to 1 + 2x^2 + x^4