Answer:
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Simplify each of the following expressions:
(i) (3 + √3)(2 + √2) (ii) (3 + √3)(3 - √3) (iii) (√5 + √2)² (iv) (√5 - √2)(√5 + √2)
Solution:
(i) (3 + √3)(2 + √2)
By Distributive property, (a + b) (c + d) = ac + ad + bc + bd
(3 + √3)(2 + √2) = 3 × 2 + 3√2 + √3 × 2 + √3 × √2
= 6 + 3√2 + 2√3 + √6
(ii) (3 + √3)(3 - √3)
Using the identity, (a + b) (a - b) = a² - b²
(3 + √3)(3 - √3) = 3² - (√3)²
= 9 - 3
= 6
(iii) (√5 + √2)²
Using the identity, (a + b) ² = a² + 2ab + b²
(√5 + √2)² = (√5)² + (2×√5×√2) + (√2)²
= (5 + 2√10 + 2)
= 7 + 2√10
(iv) (√5 - √2)( √5 + √2)
Using the identity (a + b) (a - b) = a² - b²
(√5 - √2)( √5 + √2) = (√5)² - (√2)²
= 5 - 2
= 3
(i) 7 + 2√10 (ii) 6 + 3√2 + 2√3 + √6 (iii) 5 - 2√6
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Answers & Comments
Answer:
Book a trial class
Simplify each of the following expressions:
(i) (3 + √3)(2 + √2) (ii) (3 + √3)(3 - √3) (iii) (√5 + √2)² (iv) (√5 - √2)(√5 + √2)
Solution:
(i) (3 + √3)(2 + √2)
By Distributive property, (a + b) (c + d) = ac + ad + bc + bd
(3 + √3)(2 + √2) = 3 × 2 + 3√2 + √3 × 2 + √3 × √2
= 6 + 3√2 + 2√3 + √6
(ii) (3 + √3)(3 - √3)
Using the identity, (a + b) (a - b) = a² - b²
(3 + √3)(3 - √3) = 3² - (√3)²
= 9 - 3
= 6
(iii) (√5 + √2)²
Using the identity, (a + b) ² = a² + 2ab + b²
(√5 + √2)² = (√5)² + (2×√5×√2) + (√2)²
= (5 + 2√10 + 2)
= 7 + 2√10
(iv) (√5 - √2)( √5 + √2)
Using the identity (a + b) (a - b) = a² - b²
(√5 - √2)( √5 + √2) = (√5)² - (√2)²
= 5 - 2
= 3
Answer:
(i) 7 + 2√10 (ii) 6 + 3√2 + 2√3 + √6 (iii) 5 - 2√6