Answer:
a) -4
b)
x h [f(x+h) - f(x)] / h
3 2 -4
3 1 -4
3 0.1 -4
3 0.01 -4
Explanation:
a) The difference quotient is:
[f(x+h) - f(x)] / h
Our function is -4x + 7, then:
f(x+h) = -4(x+h) + 7 = -4x -4h + 7
f(x) = -4x + 7
f(x+h) - f(x) = -4x -4h + 7 - (-4x + 7 )= -4x -4h + 7 +4x - 7 = -4h
Finally:
[f(x+h) - f(x)] / h = -4h/h = -4
b)
First point in the table:
x = 3
h = 2
f(x+h) = -4(3+2) + 7 = -13
f(x) = -4(3) + 7 = -5
f(x+h) - f(x) = -13 -(-5) = -8
[f(x+h) - f(x)] / h = -8 / 2 = -4
Second point in the table:
x = 3
h = 1
f(x+h) = -4(3+1) + 7 = -9
f(x) = -4(3) + 7 = -5
f(x+h) - f(x) = -9 -(-5) = -4
[f(x+h) - f(x)] / h = -4 / 1 = -4
Third point in the table:
x = 3
h = 0.1
f(x+h) = -4(3+0.1) + 7 = -5.4
f(x) = -4(3) + 7 = -5
f(x+h) - f(x) = -5.4 -(-5) = -0.4
[f(x+h) - f(x)] / h = -0.4 / 0.1 = -4
Fourth point in the table:
x = 3
h = 0.01
f(x+h) = -4(3+0.01) + 7 = -5.04
f(x) = -4(3) + 7 = -5
f(x+h) - f(x) = -5.04 -(-5) = -0.04
[f(x+h) - f(x)] / h = -0.04 / 0.01 = -4