answer:For a triangle to be formed, the sum of the lengths of any two sides must be greater than the length of the third side. Using this rule, we can set up inequalities for the three sides: begin{align*} 5 + 9 &> n, 5 + n &> 9, 9 + n &> 5. end{align*} Simplifying these inequalities gives us: begin{align*} 14 &> n, n &> 4, n &> -4. end{align*} From these inequalities, we can see that n must be greater than 4 and less than 14. The whole number values of n that satisfy these conditions are 5, 6, 7, 8, 9, 10, 11, 12, and 13. The sum of these values is 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 = boxed{81}.The answer is: 81

answer:We are given that x + 2y = 4 and xy = -8. Squaring the first equation, we get x^2 + 4xy + 4y^2 = 16. Substituting xy = -8, we have x^2 + 4y^2 - 32 = 16. Adding 32 to both sides, we get x^2 + 4y^2 = boxed{48}. The answer is: 48

answer:The number of plants in each row is 10, and there are 30 rows, so there are a total of 10 x 30 = 300 tomato plants. Each tomato plant yields 20 pieces of tomatoes, so the total number of tomatoes is 300 x 20 = 6000. 6000 The answer is: 6000

answer:To find the x-intercepts of the graph, we set y to 0 and solve for x. Plugging in y = 0 into the equation, we get x = 1. Therefore, the graph has only one x-intercept, which is (1, 0). So the number of x-intercepts is boxed{1}.The answer is: 1