Let the points (112,α)\left(\frac{11}{2}, \alpha\right) lie on or inside the triangle with sides x+y=11x + y = 11, x+2y=16x + 2y = 16, and 2x+3y=292x + 3y = 29. Then the product of the smallest and the largest values of α\alpha is equal to:

Answer: 33

Step-by-step solution

Step 1: Find the vertices of the triangle

First, we need to find the vertices of the triangle formed by the given lines. We will find the intersection points of each pair of lines. Let the lines be L1:x+y=11L_1: x + y = 11, L2:x+2y=16L_2: x + 2y = 16, and L3:2x+3y=29L_3: 2x + 3y = 29.

Step 2: Calculate intersection points

Solving L1L_1 and L2L_2: Subtracting L1L_1 from L2L_2 gives y=5y = 5. Substituting into L1L_1 gives x=6x = 6. So, vertex A=(6,5)A = (6, 5). Solving L2L_2 and L3L_3: Multiply L2L_2 by 2 to get 2x+4y=322x + 4y = 32. Subtract L3L_3 from this to get y=3y = 3. Substituting into L2L_2 gives x+2(3)=16  ⟹  x=10x + 2(3) = 16 \implies x = 10. So, vertex B=(10,3)B = (10, 3). Solving L3L_3 and L1L_1: Multiply L1L_1 by 2 to get 2x+2y=222x + 2y = 22. Subtract this from L3L_3 to get y=7y = 7. Substituting into L1L_1 gives x+7=11  ⟹  x=4x + 7 = 11 \implies x = 4. So, vertex C=(4,7)C = (4, 7). Wait, let's recheck the intersection of L2L_2 and L3L_3. L2:x+2y=16  ⟹  x=16−2yL_2: x + 2y = 16 \implies x = 16 - 2y Substitute into L3:2(16−2y)+3y=29  ⟹  32−4y+3y=29  ⟹  32−y=29  ⟹  y=3L_3: 2(16 - 2y) + 3y = 29 \implies 32 - 4y + 3y = 29 \implies 32 - y = 29 \implies y = 3. Then x=16−2(3)=16−6=10x = 16 - 2(3) = 16 - 6 = 10. So B=(10,3)B = (10, 3). Let's recheck the intersection of L1L_1 and L2L_2: L1:x+y=11L_1: x + y = 11 L2:x+2y=16L_2: x + 2y = 16 Subtracting L1L_1 from L2L_2: (x+2y)−(x+y)=16−11  ⟹  y=5(x + 2y) - (x + y) = 16 - 11 \implies y = 5. Substitute y=5y=5 into L1L_1: x+5=11  ⟹  x=6x + 5 = 11 \implies x = 6. So A=(6,5)A = (6, 5). Let's recheck the intersection of L1L_1 and L3L_3: L1:x+y=11  ⟹  x=11−yL_1: x + y = 11 \implies x = 11 - y L3:2x+3y=29L_3: 2x + 3y = 29 Substitute x=11−yx = 11 - y into L3L_3: 2(11−y)+3y=29  ⟹  22−2y+3y=29  ⟹  22+y=29  ⟹  y=72(11 - y) + 3y = 29 \implies 22 - 2y + 3y = 29 \implies 22 + y = 29 \implies y = 7. Substitute y=7y=7 into L1L_1: x+7=11  ⟹  x=4x + 7 = 11 \implies x = 4. So C=(4,7)C = (4, 7). The vertices are A(6,5)A(6, 5), B(10,3)B(10, 3), and C(4,7)C(4, 7).

Step 3: Substitute the point into the line equations

The point P(112,α)P\left(\frac{11}{2}, \alpha\right) lies on or inside the triangle. This means that when we substitute the coordinates of PP into the equations of the lines, the resulting values must satisfy the inequalities that define the interior of the triangle. To determine the correct inequality direction, we can test a point known to be inside the triangle, for example, the centroid. The centroid is (6+10+43,5+3+73)=(203,5)\left(\frac{6+10+4}{3}, \frac{5+3+7}{3}\right) = \left(\frac{20}{3}, 5\right). For L1:x+y−11=0L_1: x + y - 11 = 0, Pc=203+5−11=20+15−333=23>0P_c = \frac{20}{3} + 5 - 11 = \frac{20+15-33}{3} = \frac{2}{3} > 0. So for points inside, x+y−11≥0x+y-11 \ge 0. For L2:x+2y−16=0L_2: x + 2y - 16 = 0, Pc=203+2(5)−16=203+10−16=203−6=20−183=23>0P_c = \frac{20}{3} + 2(5) - 16 = \frac{20}{3} + 10 - 16 = \frac{20}{3} - 6 = \frac{20-18}{3} = \frac{2}{3} > 0. So for points inside, x+2y−16≥0x+2y-16 \ge 0. For L3:2x+3y−29=0L_3: 2x + 3y - 29 = 0, Pc=2(203)+3(5)−29=403+15−29=403−14=40−423=−23<0P_c = 2\left(\frac{20}{3}\right) + 3(5) - 29 = \frac{40}{3} + 15 - 29 = \frac{40}{3} - 14 = \frac{40-42}{3} = -\frac{2}{3} < 0. So for points inside, 2x+3y−29≤02x+3y-29 \le 0. Now, substitute x=112x = \frac{11}{2} into these inequalities: 1. x+y−11≥0  ⟹  112+α−11≥0  ⟹  α−112≥0  ⟹  α≥112x + y - 11 \ge 0 \implies \frac{11}{2} + \alpha - 11 \ge 0 \implies \alpha - \frac{11}{2} \ge 0 \implies \alpha \ge \frac{11}{2} 2. x+2y−16≥0  ⟹  112+2α−16≥0  ⟹  2α≥16−112  ⟹  2α≥32−112  ⟹  2α≥212  ⟹  α≥214x + 2y - 16 \ge 0 \implies \frac{11}{2} + 2\alpha - 16 \ge 0 \implies 2\alpha \ge 16 - \frac{11}{2} \implies 2\alpha \ge \frac{32 - 11}{2} \implies 2\alpha \ge \frac{21}{2} \implies \alpha \ge \frac{21}{4} 3. 2x+3y−29≤0  ⟹  2(112)+3α−29≤0  ⟹  11+3α−29≤0  ⟹  3α−18≤0  ⟹  3α≤18  ⟹  α≤62x + 3y - 29 \le 0 \implies 2\left(\frac{11}{2}\right) + 3\alpha - 29 \le 0 \implies 11 + 3\alpha - 29 \le 0 \implies 3\alpha - 18 \le 0 \implies 3\alpha \le 18 \implies \alpha \le 6

Step 4: Determine the range of α\alpha

We have the following conditions for α\alpha: α≥112=5.5\alpha \ge \frac{11}{2} = 5.5 α≥214=5.25\alpha \ge \frac{21}{4} = 5.25 α≤6\alpha \le 6 Combining these inequalities, we get: α≥max⁡(5.5,5.25)  ⟹  α≥5.5\alpha \ge \max(5.5, 5.25) \implies \alpha \ge 5.5 So, the range for α\alpha is 5.5≤α≤65.5 \le \alpha \le 6.

Step 5: Calculate the product of smallest and largest values

The smallest value of α\alpha is 112\frac{11}{2} and the largest value of α\alpha is 66. The product of these values is 112×6=11×3=33\frac{11}{2} \times 6 = 11 \times 3 = 33.

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