Question

8.4 add, subtract, and multiply radical expressions
score: 17.8/22 answered: 18/22
question 19
expand and simplify.
$(8 - 7\sqrt{6})(-6 - 5\sqrt{6})=$
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Explanation:

Step1: Use FOIL method

$(8 - 7\sqrt{6})(-6 - 5\sqrt{6})=8\times(-6)+8\times(- 5\sqrt{6})+(-7\sqrt{6})\times(-6)+(-7\sqrt{6})\times(-5\sqrt{6})$

Step2: Calculate each product

$8\times(-6)=-48$; $8\times(-5\sqrt{6})=-40\sqrt{6}$; $(-7\sqrt{6})\times(-6) = 42\sqrt{6}$; $(-7\sqrt{6})\times(-5\sqrt{6})=(-7)\times(-5)\times\sqrt{6}\times\sqrt{6}=35\times6 = 210$

Step3: Combine like - terms

$-48-40\sqrt{6}+42\sqrt{6}+210=(-48 + 210)+(-40\sqrt{6}+42\sqrt{6})=162 + 2\sqrt{6}$

Answer:

$162 + 2\sqrt{6}$