CUET Preparation Today
If x - 2y = 3 and xy = 5, find the value of $x^2 - 4y^2$. |
22 21 23 20 |
21 |
We know that, If x - y = n then, x + y = \(\sqrt {n^2 + 4xy}\) a2 - b2 = (a + b) (a – b) Given data, If x - 2y = 3 xy = 5, then, x + 2y = \(\sqrt {3^2 + 4(2×5)}\) = 7 find the value of $x^2 - 4y^2$ = ( x - 2y)( x + 2y) = $x^2 - 4y^2$ = 3 × 7 = 21 |
