expand (3x -7) ²
find 51² - 49² using identity
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Answered by
8
Answer:
(3x-7)² [(a-b)²=a²-2ab+b²]
=3x²-2×3x×7+7²
=9x²-42x+49
Answered by
40
1) ( 3x - 7 ) ²
Using the identity
❥ ( a - b ) ² = a² - 2ab + b²
( 3x ) ² - 2 x 3x x 7 + ( 7 ) ²
9x² - 42x + 49
2) 51² - 49²
Using the identity
❥ a² - b² = ( a + b ) ( a - b )
( 51 + 49 ) ( 51 - 49 )
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