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Derivative help - calculus!?
How do you calculate the derivative of 2^x + 3^x where x = -0.1?
on paper, without the nice ln() function on the calculator...
4 Answers
- WilliamLv 41 decade ago
if the value of x is predetermined
than all you can do is substitute
the known value into the equation
2^(-0.1)+3^(-0.1)
Raise 2 to the -0.1th power.
0.933+3^(-0.1)
Raise 3 to the -0.1th power.
0.933+0.896
Add 0.896 to 0.933 to get 1.829.
1.829
However
they want you to determine the
derivative first then plug in the
x=-0.1
2^(x)+3^(x)
The derivative of 2^(x) is 2^(x)*ln(2).
(d)/(dx) 2^(x)+3^(x)=
2^(x)*ln(2)+(d)/(dx) 3^(x)
The derivative of 3^(x) is 3^(x)*ln(3).
(d)/(dx) 2^(x)+3^(x)=
2^(x)*ln(2)+3^(x)*ln(3)
Multiply 2^(x) by ln(2) to get 2^(x)ln(2).
(d)/(dx) 2^(x)+3^(x)=
2^(x)ln(2)+3^(x)*ln(3)
Multiply 3^(x) by ln(3) to get 3^(x)ln(3).
(d)/(dx) 2^(x)+3^(x)=
2^(x)ln(2)+3^(x)ln(3)
The derivative of 2^(x)+3^(x) is
2^(x)ln(2)+3^(x)ln(3).
now plug in the -0.1 into x
- ?Lv 41 decade ago
f(x) = 2^x + 3^x
f ' (x) = 2^x * ln(2) + 3^x * ln(3)
so f ' (-0.1) = 2^(-0.1) ln(2) + 3^(-0.1) * ln(3)
= 1.631