Using a2 minus-b2 - -a - b- -a minus- b-find-i-512 minus-492 -ii-1-02-2 minus- -0-98-2-iii-1532 minus- 1472 -iv-12-12 minus-7-92

(i) 512 minus;492 = (51 + 49) (51 minus; 49) = (100) (2) = 200(ii) (1.02)2 minus; (0.98)2 = (1.02 + 0.98) (1.02 shy; minus; 0.98) = (2) (0.04) = 0 ...

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Byju's Answer

Standard VII

Mathematics

Addition and Subtraction of Decimals

Using a2 m...

Question

Using a²−b² = (a + b) (a − b),find
(i) 51² −49² (ii) (1.02)² − (0.98)² (iii) 153² − 147²
(iv) 12.1² −7.9²

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Solution

(i) 51² −49² = (51 + 49) (51 − 49)
= (100) (2) = 200
(ii) (1.02)²− (0.98)² = (1.02 + 0.98) (1.02 − 0.98)
= (2) (0.04) = 0.08
(iii) 153² −147² = (153 + 147) (153 − 147)
=(300) (6) = 1800
(iv) 12.1² −7.9² = (12.1 + 7.9) (12.1 − 7.9)
=(20.0) (4.2) = 84

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Similar questions

Q. Using

a^{2} - b^{2} = (a + b) (a - b)

, find
(i)

51^{2} - 49^{2}

(ii)

{1.02}^{2} - {0.98}^{2}

(iii)

153^{2} - 147^{2}

(iv)

{12.1}^{2} - {7.9}^{2}

Q. Using

a^{2} - b^{2} = (a + b) (a - b)

, find

(i) 153^{2} - 147^{2} (i i) {12.1}^{2} - {7.9}^{2}

Using a²-b²=(a+b)(a-b) find:

i. 51² - 49²

ii. (1.02)² - (0.98)²

Using $a^{2} - b^{2} = (a + b) (a - b)$ , find
${1.02}^{2} - {0.98}^{2}$

Q. Using

a^{2} - b^{2} = (a + b) (a - b)

, find

153^{2} - 147^{2}

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Using a2 −b2 = (a + b) (a − b),find(i) 512 −492 (ii) (1.02)2 − (0.98)2 (iii) 1532 − 1472 (iv) 12.12 −7.92

(i) 512 −492 = (51 + 49) (51 − 49) = (100) (2) = 200(ii) (1.02)2− (0.98)2 = (1.02 + 0.98) (1.02 ­− 0.98) = (2) (0.04) = 0.08(iii) 1532 −1472 = (153 + 147) (153 − 147)=(300) (6) = 1800(iv) 12.12 −7.92 = (12.1 + 7.9) (12.1 − 7.9)=(20.0) (4.2) = 84

Using a²−b² = (a + b) (a − b),find
(i) 51² −49² (ii) (1.02)² − (0.98)² (iii) 153² − 147²
(iv) 12.1² −7.9²

(i) 51² −49² = (51 + 49) (51 − 49)
= (100) (2) = 200
(ii) (1.02)²− (0.98)² = (1.02 + 0.98) (1.02 − 0.98)
= (2) (0.04) = 0.08
(iii) 153² −147² = (153 + 147) (153 − 147)
=(300) (6) = 1800
(iv) 12.1² −7.9² = (12.1 + 7.9) (12.1 − 7.9)
=(20.0) (4.2) = 84