Big Ideas Math Algebra 2, 2014
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Big Ideas Math Algebra 2, 2014 View details
4. Solving Radical Equations and Inequalities
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Exercise 46 Page 267

Practice makes perfect
a

To find the heights of the kangaroo and snowboarder, we substitute the hang time, t, into the function and solve for h.

Kangaroo

t=0.5sqrt(h)
0.81=0.5sqrt(h)
â–¼
Solve for h
1.62=sqrt(h)
2.6244=h
h=2.6244
h≈ 2.62

The jump height of a kangaroo is about 2.62 feet.

Snowboarder

t=0.5sqrt(h)
1.21=0.5sqrt(h)
â–¼
Solve for h
2.42=sqrt(h)
5.8564=h
h=5.8564
h≈ 5.86

The jump height of a snowboarder is about 5.86 feet.

b

To double the hang times, we multiply the times given in Part A by 2.

hang time kangaroo:& 0.81(2)=1.62 s hang time snowboarder:& 1.21(2)=2.42 sNow we can calculate the new heights of the kangaroo and snowboarder.

Kangaroo

t=0.5sqrt(h)
1.62=0.5sqrt(h)
â–¼
Solve for h
3.24=sqrt(h)
10.4976=h
h=10.4976
h≈ 10.50

The height of the kangaroo is about 10.5 feet when the hang time from Part A is doubled.

Snowboarder

t=0.5sqrt(h)
2.42=0.5sqrt(h)
â–¼
Solve for h
4.84=sqrt(h)
23.4256=h
h=23.4256
h≈ 23.43

The height of the snowboarder is about 23.43 feet when the hang time from Part A is doubled.

c

To investigate how the jump increases when hang time doubles, we can divide the height when the time is T and compare it with 2T, which is double that of T.

Time is T

t=0.5sqrt(h)
T=0.5sqrt(h)
â–¼
Solve for h
2T=sqrt(h)
(2T)^2=h
4T^2=h
h=4T^2
The height when the time is T is 4T^2

Time is 2T

t=0.5sqrt(h)
2T=0.5sqrt(h)
â–¼
Solve for h
4T=sqrt(h)
(4T)^2=h
16T^2=h
h=16T^2

The height when the time is 2T is 16T^2. If we divide the height when the hang time is 2T by the height when the hang time is T, we can determine how much the height increases.

h_(2T)/h_T
16T^2/4T^2
16/4
4

When the hang time doubles, the height quadruples.