Question

If x-2y=3 and xy=5, find the value of xsquare-4ysquare

Answer 1

Answer:

x² + 4y²  = 29

Step-by-step explanation:

given, x-2y=3 and xy=5,

to find x²-4y²,

take, x - 2y = 3

squaring on both sides, we get

(x - 2y)² = 3²

=> x² + (2y)² - 2(x)(2y) = 9

=> x² + 4y² - 4(xy) = 9

=> x² + 4y²  = 9 + 4(xy)

=> x² + 4y²  = 9 + 4(5)   (given)

=> x² + 4y²  = 9 + 20

=> x² + 4y²  = 29