Final answer:
Linear approximation uses the tangent line at a known point to estimate the values of a function near that point. Without the specific function f, we can't provide numerical estimates, but we can say that if slopes of tangent lines are negative and the tangents are getting steeper, our estimates are too large; if slopes are positive and tangents less steep, our estimates are too small.
Step-by-step explanation:
To estimate the values of f(0.9) and f(1.1) using linear approximation, we can apply the concept that the tangent line at a given point of a differentiable function provides the best linear approximation to the function near that point.
For part (a), we must know the value of the function and its derivative at a point close to 0.9 and 1.1. Without the explicit function f, we can't calculate an exact numerical estimate, but we can discuss the approach: we would use the formula f(x) ≈ f(a) + f'(a)(x - a), where a is a point near x, and f'(a) is the derivative of f at a.
For part (b), if the slopes of the tangent lines to the curve f are negative and becoming steeper, this means the actual function is decreasing faster than the linear approximation, hence our linear approximation at points 0.9 and 1.1 would be too large. Conversely, if the slopes of the tangent lines are positive and becoming less steep, our estimate would be too small because the linear approximation is not capturing the slower rate of increase of the actual function.