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**1. 64 2. (–32) Lesson 6.6, For use with pages 452-459**

Evaluate the expression. 1. 64 2 3 ANSWER 16 2. (–32) 3 5 ANSWER –8

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**3. Expand (x – 5)2 x2 – 10x + 25 4. x2 + 6x + 9 = x + 45 –9, 4**

Lesson 6.6, For use with pages Evaluate the expression. 3. Expand (x – 5)2 ANSWER x2 – 10x + 25 Solve the equation. 4. x2 + 6x + 9 = x + 45 ANSWER –9, 4

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**π 5. A cone-shaped cup has a height of 7 cm and a radius**

Lesson 6.6, For use with pages Solve the equation 5. A cone-shaped cup has a height of 7 cm and a radius of 2.5 cm. Use V = r2h to find the volume of the cup. 1 – 3 π ANSWER about 45.8 cm3

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**Solving Radical Equations**

6.6 Intermediate Algebra Solving Radical Equations

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**Write original equation.**

EXAMPLE 1 Solve a radical equation Solve = 3. 2x+7 2x+7 3 = 3 Write original equation. = 33 2x+7 3 ( )3 Cube each side to eliminate the radical. 2x+7 = 27 Simplify. 2x = 20 Subtract 7 from each side. x = 10 Divide each side by 2.

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**Substitute 10 for x. Simplify. Solution checks. EXAMPLE 1**

Solve a radical equation CHECK Check x = 10 in the original equation. 2(10)+7 3 = ? Substitute 10 for x. 27 3 = ? Simplify. = 3 3 Solution checks.

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GUIDED PRACTICE for Example 1 Solve equation. Check your solution. √ x – 9 = –1 3. (23 x – 3 ) = 4 ANSWER x = 512 ANSWER x = 11 2. ( x+25 ) = 4 x = –9 ANSWER

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EXAMPLE 2 Solve a radical equation given a function Wind Velocity where p is the air pressure (in millibars) at the center of the hurricane. Estimate the air pressure at the center of a hurricane when the mean sustained wind velocity is 54.5 meters per second. In a hurricane, the mean sustained wind velocity v (in meters per second) is given by v(p) = – p

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**Subtract 1013 from each side.**

EXAMPLE 2 Solve a radical equation given a function SOLUTION = – p v(p) Write given function. 1013 – p = 6.3 54.5 Substitute 54.5 for v(p). 8.65 1013 – p Divide each side by 6.3. (8.65)2 1013 – p 2 Square each side. 74.8 1013 –p Simplify. – 938.2 –p Subtract 1013 from each side. 938.2 p Divide each side by –1.

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EXAMPLE 2 Solve a radical equation given a function The air pressure at the center of the hurricane is about 938 millibars. ANSWER

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GUIDED PRACTICE for Example 2 4. What If? Use the function in Example 2 to estimate the air pressure at the center of a hurricane when the mean sustained wind velocity is 48.3 meters per second. about 954 mille bars. ANSWER

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**Write original equation.**

EXAMPLE 3 Standardized Test Practice SOLUTION 4x2/3 = 36 Write original equation. x2/3 = 9 Divide each side by 4. (x2/3)3/2 = 93/2 Raise each side to the power . 3 2 x = 27 Simplify. ANSWER The correct answer is D.

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**Write original equation.**

EXAMPLE 4 Solve an equation with a rational exponent Solve (x + 2)3/4 – 1 = 7. (x + 2)3/4 – 1 = 7 Write original equation. (x + 2)3/4 = 8 Add 1 to each side. (x + 2)3/4 4/3 = 8 4/3 Raise each side to the power . 4 3 x + 2 = (8 1/3)4 Apply properties of exponents. x + 2 = 24 Simplify. x + 2 = 16 Simplify. x = 14 Subtract 2 from each side.

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EXAMPLE 4 Solve an equation with a rational exponent The solution is 14. Check this in the original equation. ANSWER

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GUIDED PRACTICE for Examples 3 and 4 Solve the equation. Check your solution. x3/2 = 375 8. (x + 3)5/2 = 32 ANSWER x = 25 ANSWER x = 1 6. –2x3/4 = –16 9. (x – 5)5/3 = 243 ANSWER x = 16 ANSWER x = 32 2 3 x1/5 – = –2 7. (x + 2)2/3 +3 = 7 x = 243 ANSWER ANSWER x = –10 or 6

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**Write original equation.**

EXAMPLE 5 Solve an equation with an extraneous solution Solve x + 1 = x + 15 x + 1 = 7x + 15 Write original equation. (x + 1)2 = ( 7x + 15)2 Square each side. x2 + 2x + 1 = 7x + 15 Expand left side and simplify right side. x2 – 5x – 14 = 0 Write in standard form. (x – 7)(x + 2) = 0 Factor. x – 7 = 0 or x + 2 = 0 Zero-product property x = 7 or x = –2 Solve for x.

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EXAMPLE 5 Solve an equation with an extraneous solution CHECK Check x = 7 in the original equation. Check x = –2 in the x + 1 = 7x + 15 x + 1 = 7x + 15 7 + 1 ? = 7(7) + 15 –2 + 1 ? = 7(–2) + 15 8 = 64 ? –1 = 1 ? 8 = 8 = 1 / –1 The only solution is 7. (The apparent solution –2 is extraneous.) ANSWER

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**Write original equation.**

EXAMPLE 6 Solve an equation with two radicals x = – x . Solve SOLUTION METHOD 1 Solve using algebra. x = 3 – x Write original equation. x 2 = – x 2 Square each side. x x = 3 – x Expand left side and simplify right side. 2 x + 2 = –2x Isolate radical expression.

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**Zero-product property.**

EXAMPLE 6 Solve an equation with two radicals x + 2 = –x Divide each side by 2. x + 2 2 = ( –x)2 Square each side again. x + 2 = x2 Simplify. = x2 – x – 2 Write in standard form. = (x – 2)(x + 1) Factor. x – 2 = 0 or x + 1 = 0 Zero-product property. x = 2 or x = –1 Solve for x.

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EXAMPLE 6 Solve an equation with two radicals Check x = 2 in the original equation. Check x = – 1 in the original equation. x = 3 – x x = 3 – x = 3 – 2 ? – = 3 – (–1) ? 4 +1 = 1 ? 1 +1 = 4 ? = –1 / 3 2 = 2 The only solution is 1. (The apparent solution 2 is extraneous.) ANSWER

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EXAMPLE 6 Solve an equation with two radicals METHOD 2 Use: a graph to solve the equation. Use a graphing calculator to graph y1 = 𝑥 and y2 = 3−𝑥 . Then find the intersection points of the two graphs by using the intersect feature. You will find that the only point of intersection is (–1, 2). Therefore, –1 is the only solution of the equation x 3 – x =

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GUIDED PRACTICE for Examples 5 and 6 Solve the equation. Check for extraneous solutions 11. x – 1 2 = 4 1 x 13. 2x + 5 x + 7 = ANSWER x = 9 ANSWER x = 2 x + 6 – 2 x – 2 14. = 12. 10x + 9 = x + 3 ANSWER x = 0,4 ANSWER x = 3

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