大师作文网定积分求面积太困了,做不下去...
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定积分求面积
太困了,做不下去...
太困了,做不下去...
y = e^x = e^18
x = 18,A(18,e^18)
y = e^(2x) = e^18,x = 9
S = S1 + S2
= ∫₀⁹[e^(2x) - e^x]dx + ∫₉¹⁸[e^18 - e^x]dx
= [(1/2)e^(2x) - e^x]|₀⁹ + [(e^18)x - e^x]|₉¹⁸
= (1/2)e^18 - e^9 - (1/2 - 1) + (18e^18 - e^18) - (9e^18 - e^9)
= (17e^18 + 1)/2
x = 18,A(18,e^18)
y = e^(2x) = e^18,x = 9
S = S1 + S2
= ∫₀⁹[e^(2x) - e^x]dx + ∫₉¹⁸[e^18 - e^x]dx
= [(1/2)e^(2x) - e^x]|₀⁹ + [(e^18)x - e^x]|₉¹⁸
= (1/2)e^18 - e^9 - (1/2 - 1) + (18e^18 - e^18) - (9e^18 - e^9)
= (17e^18 + 1)/2