maths legend please help
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⇒ (3x + y - 5)(3x - y - 5)
⇒ (3x - 5 + y)(3x - 5 - y)
⇒ [(3x - 5) + y ] [(3x - 5) - y ]
Using:
(a + b)(a - b) = a² - b²
In question, a = (3x - 5) & b = y
⇒ (3x - 5)² - y²
Using:
(a - b)² = a² + b² - 2ab for (3x-5)²
⇒ (3x)² + 5² - 2(3x)(5) - y²
⇒ 9x² + 25 - 30x - y²
⇒ 9x² - y² - 30x + 25
Answered by
2
Answer:
⇒ (3x + y - 5)(3x - y - 5)
⇒ (3x - 5 + y)(3x - 5 - y)
⇒ [(3x - 5) + y ] [(3x - 5) - y ]
Using:
(a + b)(a - b) = a² - b²
In question, a = (3x - 5) & b = y
⇒ (3x - 5)² - y²
Using:
(a - b)² = a² + b² - 2ab for (3x-5)²
⇒ (3x)² + 5² - 2(3x)(5) - y²
⇒ 9x² + 25 - 30x - y²
⇒ 9x² - y² - 30x + 25
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