Question

5. Using the identity (a² - b²) = (a + b)(a - b), evaluate each of the following:
(i) 82²-18²
(ii) (15.8)² - (9.2)²
(iii) (0.8)² - (0.2)²
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Answer 1

Answer:

evaluate wale Mein first question in 82 square minus 18 and ka whole square is that means 111 bracken 82 - 18 and another vector 2 + 18 to solve it and get answer like this you also solved second and third questions

1st question

(82-18) (82+18)

(64)*(100)

answer is...... 6400

Answer 2

Given :–

• Using identity, (a² - b²) = (a – b)(a + b).

Required :–

Evaluate the followings :–

1. 82² – 18²
2. (15.8)² – (9.2)²
3. (0.8)² – (0.2)²

Solution :–

1. (82)² – (18)²

Given identity, (a² - b²) = (a – b)(a + b)

Here,

• a = 82
• b = 18

Now, put the values of a and b in the given identity.

⟹ (82 – 18)(82 + 18)

Now, solve both the brackets.

⟹ (64)(100)

Now, open both the brackets.

⟹ 6400

Hence,

6400 is the answer.

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2. (15.8)² – (9.2)²

Given identity, (a² - b²) = (a – b)(a + b)

Here,

• a = 15.8
• b = 9.2

Now, put the values of a and b in the given identity.

⟹ (15.8 – 9.2)(15.8 + 9.2)

Now, solve both the brackets.

⟹ (6.6)(25.0)

⟹ (6.6)(25)

Now, open both the brackets.

⟹ 165

Hence,

165 is the answer.

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3. (0.8)² – (0.2)²

Given identity, (a² - b²) = (a – b)(a + b)

Here,

• a = 0.8
• b = 0.2

Now, put the values of a and b in the given identity.

⟹ (0.8 – 0.2)(0.8 + 0.2)

Now, solve both the brackets.

⟹ (0.6)(1.0)

⟹ (0.6)(1)

Now, open both the brackets.

⟹ 0.6

Hence,

0.6 is the answer.