Radical Equations
DAY 6
1.
Beaufort Wind Scale
The Beaufort wind scale was devised to measure wind speed. The Beaufort numbers B, which
range from 0 to 12, can be modeled by B = 1.69 s + 4.45 − 3.49 , where s is the speed (in miles
per hour) of the wind. Find the wind speed that corresponds to the Beaufort number B=11.
2.
In order to compete in the America’s Cup sailboat race, a boat must satisfy the rule:
l + 1.25 s − 9.8 3 d
≤ 24 , where l is the length (in meters) of the boat, s is the area (in square
0.679
meters) of the sails, and d is the volume (in cubic meters) of water displaced by the boat. If a boat
has a length of 20 meters and a sail area of 300 square meters, what is the minimum allowable value
for d?
3.
You are trying to determine the height of a truncated pyramid that cannot be measured directly. The
height h and slant height l of a truncated pyramid are related by the formula:
1
l = h 2 + (b2 − b1 )2 , where b1 and b2 are the lengths of the upper and lower bases of the
4
pyramid, respectively. If l = 5, b1 = 2, and b2 = 4, what is the height of the pyramid?
1.
Solving a Simple Radical Equation
a. Original equation.
3x
−4=0
b. Isolate the radical.
c. Square/Cube each side.
d. Simplify.
2.
Solving an Equation with Rational Exponents
a. Original Equation.
3(x + 2) −1 = 23
3
4
b. Isolate the power
c. Raise each side to the (4/3) power.
d. Apply properties of roots.
e. Simplify.
3.
Solving an Equation with One Radical
a. Write original equation.
b. Isolate the radical.
c. Square/Cube each side.
d. Simplify.
e. Add 7 to each side.
f. Divide each side by 4.
4.
Solving an Equation with Two Radicals
4x − 7 + 2 = 5
a. Original equation.
3x + 2 − 2 x = 0
b. Add 2 x to both sides.
c. Square each side.
d. Simplify.
e. Solve for x.
5.
An Equation with an Extraneous Solution
a. Original Equation.
b. Square each side.
c. Expand left side and simplify right side.
d. Write in standard form.
e. Factor.
f. Zero Product Property.
g. Simplify.
CHECK
Extraneous Solution:
x −4=
2x
Solve each radical equation. Show all steps toward your solution!
1.
2.
3.
4.
5.
7.
9.
2(x −1)1/2 = 5
2x = 250
3
2
6.
8.
10.
Solve each radical equation. These will all lead to a quadratic equation that you will need
to solve. Do you remember how? Remember to check your solutions!
1.
2.
Check:
Check:
3.
4.
Check:
Check:
Solve each of the following cube root equations:
1.
2.
4.
1
(x + 4) 3 + 7 = 4
5.
3.
6.
Solve each of the following cubic equations:
1.
2.
3.
4.
6.
5.
3
3x + 2 = 3 x + 5
Challenges
1.
x +5 = 5− x
2.
3.
2x + 4 + 3x − 5 = 4
4.
2x + 3 = 3 − 2x
1 2x − 5 − 1 3x + 4 = 1
2
2