answer:Solution: Since f(x)= begin{cases} x+4 & x < 0 x-4 & x > 0 end{cases}, therefore f(-3)=-3+4=1 f[f(-3)]=f(1)=1-4=-3. Hence, the answer is: boxed{-3}. To find f(-3), substitute -3 into the formula for the segment where x < 0. Then, substitute the result into the corresponding formula to find the function value. This problem tests the ability to find the function value of a piecewise function: according to the range of the independent variable, substitute it into the corresponding formula to find the function value. The key concept of studying the graph and properties of a piecewise function is segmented processing. Specifically, the domain and range of a piecewise function are the union of the x and y value ranges of each segment, respectively. The evenness, oddness, and monotonicity of a piecewise function should be proven separately for each segment. The maximum value of a piecewise function is the maximum among the maximum values of each segment.

answer:- First, calculate left(frac{1}{3}right)^2. We have: [ left(frac{1}{3}right)^2 = frac{1}{3} cdot frac{1}{3} = frac{1}{9} ] - Next, multiply frac{1}{9} by left(frac{1}{8}right): [ frac{1}{9} cdot frac{1}{8} = frac{1}{72} ] - Therefore, the computation is: [ left(frac{1}{3}right)^2 cdot left(frac{1}{8}right) = boxed{frac{1}{72}} ]

answer:To find the non-condiment weight of the sandwich, subtract the weight of the condiments from the total weight: [ 150 - 45 = 105 text{ grams} ] Next, calculate the fraction of the sandwich that is not condiments: [ frac{105}{150} ] Simplify the fraction: [ frac{105}{150} = frac{7}{10} ] Convert this fraction to a percentage: [ frac{7}{10} times 100% = 70% ] Thus, boxed{70%} of the sandwich is not condiments.

answer:According to the problem, the circle x^2+y^2-4x+3=0 can be rewritten as (x-2)^2+y^2=1, with the center at (2,0) and a radius of 1. Let (a,b) be the point symmetric to (2,0) about the line y=frac{sqrt{3}}{3}x. Then we have the system of equations: begin{cases} frac{b}{a-2} times frac{sqrt{3}}{3} = -1 frac{b}{2} = frac{sqrt{3}}{3} times frac{a+2}{2} end{cases} Solving this system, we find a=1 and b=sqrt{3}. Therefore, the center of the desired circle is (1,sqrt{3}) and its radius is 1. The equation of this circle is (x-1)^2+(y-sqrt{3})^2=1. Hence, the answer is boxed{D}. This problem tests the understanding of the relationship between lines and circles, focusing on finding the center of the desired circle. It is a basic problem.