For 2 X**3 + -4 X**2 + 5 X
The slope at -2 is 45
The slope at 1 is 3
The slope at 3 is 35

For 12 X**5 + -87 X**3 + 40 X + -23.3
The slope at -2 is -44
The slope at 1 is -161
The slope at 3 is 2551

For 3 X**7 + -3 X**6 + -5 X**5 + 42 X**4 + 12
The slope at -2 is 176
The slope at 1 is 146
The slope at 3 is 13446

For -42 X**4 + 19 X**2 + 2.5 X + 3
The slope at -2 is 1270.5
The slope at 1 is -127.5
The slope at 3 is -4419.5

For -7 X**6 + -4 X**5 + 12 X**3 + -18 X**2 + 8.3
The slope at -2 is 1240
The slope at 1 is -62
The slope at 3 is -11610

Sum polynomial:
3 X**7 + -10 X**6 + 3 X**5 + -73 X**3 + -3 X**2 + 47.5 X
Derivative:
21 X**6 + -60 X**5 + 15 X**4 + -219 X**2 + -6 X + 47.5

At -2 the value is -643; the slope is 2687.5
At 1 the value is -32.5; the slope is -201.5
At 3 the value is -1855.5; the slope is 2.5