Math Problem Statement

2(2root10+2root8)-root2/(root5-2)

Solution

Let's break this expression down and solve it step by step.

Given:
2(210+28)2522 \left( 2\sqrt{10} + 2\sqrt{8} \right) - \frac{\sqrt{2}}{\sqrt{5} - 2}

Step 1: Simplify inside the parentheses

First, simplify the expression inside the parentheses: 2(210+28)=2210+228=410+482\left( 2\sqrt{10} + 2\sqrt{8} \right) = 2 \cdot 2\sqrt{10} + 2 \cdot 2\sqrt{8} = 4\sqrt{10} + 4\sqrt{8}

Now, let's simplify 484\sqrt{8}. Since 8=4×2=22\sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2}, we can write: 48=422=824\sqrt{8} = 4 \cdot 2\sqrt{2} = 8\sqrt{2}

So the expression now becomes: 410+824\sqrt{10} + 8\sqrt{2}

Step 2: Deal with the fraction

Next, simplify the fraction 252\frac{\sqrt{2}}{\sqrt{5} - 2}.

To rationalize the denominator, multiply both the numerator and denominator by the conjugate of the denominator, 5+2\sqrt{5} + 2: 2525+25+2=2(5+2)(5)222=2(5+2)54=2(5+2)1\frac{\sqrt{2}}{\sqrt{5} - 2} \cdot \frac{\sqrt{5} + 2}{\sqrt{5} + 2} = \frac{\sqrt{2}(\sqrt{5} + 2)}{(\sqrt{5})^2 - 2^2} = \frac{\sqrt{2}(\sqrt{5} + 2)}{5 - 4} = \frac{\sqrt{2}(\sqrt{5} + 2)}{1}

Thus: 252=2(5+2)\frac{\sqrt{2}}{\sqrt{5} - 2} = \sqrt{2}(\sqrt{5} + 2)

Step 3: Combine the two parts

Now, substitute back into the original expression: 410+822(5+2)4\sqrt{10} + 8\sqrt{2} - \sqrt{2}(\sqrt{5} + 2)

Distribute 2\sqrt{2} on the last term: 2(5+2)=25+22=10+22\sqrt{2}(\sqrt{5} + 2) = \sqrt{2} \cdot \sqrt{5} + \sqrt{2} \cdot 2 = \sqrt{10} + 2\sqrt{2}

Now substitute this back into the expression: 410+82(10+22)4\sqrt{10} + 8\sqrt{2} - (\sqrt{10} + 2\sqrt{2})

Step 4: Combine like terms

Now combine like terms: (41010)+(8222)=310+62(4\sqrt{10} - \sqrt{10}) + (8\sqrt{2} - 2\sqrt{2}) = 3\sqrt{10} + 6\sqrt{2}

Final Answer:

310+62\boxed{3\sqrt{10} + 6\sqrt{2}}

Would you like more details or have any other questions?


Here are 5 related questions for further practice:

  1. Simplify 18+32\sqrt{18} + \sqrt{32}.
  2. Rationalize the denominator: 2375\frac{2\sqrt{3}}{\sqrt{7} - \sqrt{5}}.
  3. Simplify 3(47+3)233(4\sqrt{7} + \sqrt{3}) - 2\sqrt{3}.
  4. Simplify 2(12+27)2\left( \sqrt{12} + \sqrt{27} \right).
  5. Rationalize the denominator: 62+1\frac{\sqrt{6}}{\sqrt{2} + 1}.

Tip: When rationalizing denominators, always look for the conjugate of the denominator to eliminate the square roots!

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Math Problem Analysis

Mathematical Concepts

Radicals
Rationalizing Denominators
Simplification

Formulas

√(a * b) = √a * √b
(a - b)(a + b) = a^2 - b^2

Theorems

Conjugate theorem for rationalizing denominators

Suitable Grade Level

Grades 9-11