Question

Q1.If 3x - 7y =10 & xy = -1, find 9x^2 + 49y^2

Answer 1

Step-by-step explanation:

SOLUTION:

• 9x² + 49y² = 58.

:

Given:

→ 3x - 7y = 10 –⁠ (i)

→ xy = -1

Squaring both sides of equation (i), we get:

→ (3x - 7y)² = 10²

→ 9x² + 49y² - 2 × 3x × 7y = 100

→ 9x² + 49y² - 42xy = 100

→ 9x² + 49y² - 42 × (-1) = 100

→ 9x² + 49y² + 42 = 100

→ 9x² + 49y² = 100 - 42

→ 9x² + 49y² = 58 (Answer)

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:

• (a + b)² = a² + 2ab + b²
• a² - b² = (a + b)(a - b)
• (a + b)³ = a³ + 3ab(a + b) + b³
• (a - b)³ = a³ - 3ab(a - b) - b³
• a³ + b³ = (a + b)(a² - ab + b²)
• a³ - b³ = (a - b)(a² + ab + b²)

Answer 2

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