Homework pg 120 #25,26,28,30
25.
y  x 2  5x
y  2 x  5 at x  3
y  11
Answer is iii.
26.
3x  2 y  12  0 Solve for y .
y
3
3
x  6 Slope =
2
2
Answer is iii.
28.
a.
Find the tangents to the curve y  x 3  x at the points where the slope is 4.
y  3x 2  1
Find the x coordinates when y  4
3x 2  1  4
3x 2  3
x2  1
x  1
Equation of tangent lines:
b.
At the point (1,2):
y=4(x-1)+2
At the point (-1,-2)
y=4(x+1)-2
What is the smallest slope of the curve? The smallest slope occurs when the derivative is
at its minimum. That will occur when x = 0 and the slope = 1.
30.
y  x3
Point: (-2, -8)
Slope: y  3x 2
Tangent line:
y  12
y  12( x  2)  8
4 
,0 
 3 
X intercept: 
Y intercept: (0,16)