Practicing Success
If x2 - 2xy = 84 and x - y = -10, then the value of y is: |
2 1 4 3 |
4 |
x2 − 2xy = 84 x = y - 10 According to question, x2 − 2xy = 84 ------------(a) And x = y - 10 now, put x = y - 10 in (a) (y - 10)² - 2y(y - 10) = 84 = y² - 20y + 100 - 2y² + 20y = 84 = - y² = 84 - 100 = y² = 16 = y = 4 |