Question

If 9x^2+25y^2=181 and xy = -6, find the value of 3x+5y. please answer for solution​

Answer 1

GIVEn

If 9x^2+25y^2=181 and xy = -6, find the value of 3x+5y.

TO FINd

find the value of 3x+5y.

SOLUTIOn

• 9x² + 25y² = 181
• xy = - 6

★ Applying identity :

(a + b)² = a² + b² + 2ab

→ (3x + 5y)² = (3x)² + (5y)² + 2 × 3x × 5y

→ (3x + 5y)² = 9x² + 25y² + 30xy

→ (3x + 5y)² = 181 + 30(-6)

→ (3x + 5y)² = 181 - 180

→ (3x + 5y)² = 1

→ 3x + 5y = √1 = 1

SOMe IDENTITIEs

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