Practicing Success
If $x ≥ 03y-2x≥-12, 2x+5y ≤20$ The area of the triangle formed in the xy plane by the system of inequalities above is: |
60 30 40 50 |
30 |
given, x≥0 3y−2x≥−12 and 2x+5y≤20 first, draw the graph for equations x=0 3y−2x=−12 and 2x+5y=20 x=0 is Y-axis. Hence x≥0 includes the above region of the line. for 3y−2x=−12 substitute y=0 we get, −2x=−12⟹x=6 substitute x=0 we get, 3y=−12⟹y=−4 therefore, 3y−2x=−12 line passes through (6,0) and (0,-4) as shown in fig. Hence, 3y−2x≥−12includes the region above the line. similarly for 2x+5y=20 substitute y=0 we get, 2x=20⟹x=10 substitute x=0 we get, 5y=20⟹y=4 therefore, 2x+5y=20 line passes through (10,0) and (0,4) as shown in fig. Hence, 2x+5y≤20includes the region below the line the shaded region as shown in figure is intersection region distance between (0,4) and (0,-4) is 8 units adding 3y−2x=−12 and 2x+5y=20⟹y=1 substituting y=1 in any one of equation gives x=7.5 therefore, shaded triangle base =8 units and height = 7.5 unit Area = $\frac{1}{2}$ × base × height $=\frac{1}{2}×8×7.5=30$ |