Identify a critical point of y = ex+2 – e2x
and determine whether it is a local maximum or a local minimum.
y(x) = e^(x+2) - e^(2x)
y'(x) = e^(x+2) - 2e^(2x)
y''(x) = e^(x+2) - 4e^(2x)
Critical point when y'(x) = 0
e^(x+2) - 2e^(2x) = 0
e^(x+2) = 2e^(2x)
ln[e^(x+2)] = ln[2e^(2x)]
x+2 = 2x + ln (2)
2x - x = 2 - ln(2)
x = 2 - ln(2)
x ≈ 1.307
y(2 - ln(2)) ≈ 10.237
Critical point at (1.307, 10.237)
y''(2 - ln(2)) = 1.735E-18
y''(x) > 0, so critical point at (1.307, 10.237) is a local maximum.
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y(x) = e^(x+2) - e^(2x)
y'(x) = e^(x+2) - 2e^(2x)
y''(x) = e^(x+2) - 4e^(2x)
Critical point when y'(x) = 0
e^(x+2) - 2e^(2x) = 0
e^(x+2) = 2e^(2x)
ln[e^(x+2)] = ln[2e^(2x)]
x+2 = 2x + ln (2)
2x - x = 2 - ln(2)
x = 2 - ln(2)
x ≈ 1.307
y(2 - ln(2)) ≈ 10.237
Critical point at (1.307, 10.237)
y''(x) = e^(x+2) - 4e^(2x)
y''(2 - ln(2)) = 1.735E-18
y''(x) > 0, so critical point at (1.307, 10.237) is a local maximum.