this is just algebra I, after finding the slope of the tangent line...
since y = x^(1/3)
y' = 1/3 x^-(2/3)
y(27) = 3
y'(27) = 1/9
So, now you have a point and a slope, so the line is
y-3 = 1/9 (x-27)
I'll let you massage the equation.
Now you can use that line to find y(27.05)
Or, you can note that
dy = 1/9 dx
and dx = 0.05,
so you can add dy to y to approximate y(27.05)
Hint, using the line or using the differentials will give the same answer.
Use linear approximation, i.e. the tangent line, to approximate cube root of 27.05 as follows. Let f(x) = cube root of x and find the equation of the tangent line to f(x) at x = 27 in the form y = mx+b.
Note: The values of m and b are rational numbers which can be computed by hand. You need to enter expressions which give m and b exactly. You may not have a decimal point in the answers to either of these parts.
A. m = ?
B. b= ?
C.Using these values, find the approximation. Cube root of 27.05 = ?
1 answer