x + √x - y - √y = (x - y) + (√x - √y)
= ((√x)² - (√y)²) + (√x - √y)
= (√x - √y)(√x + √y) + (√x - √y)
= (√x - √y)(√x + √y + 1)
1 - 2√a + a = 1² -2.1.√a + (√a)² = (1 - √a)²
-25 + 10√a - a = -(a - 10√a + 25)
= -((√a)² - 2.√a.5 + 5²)
= -(√a - 5)²
-√x + 7 - 6√x = 7 - 7√x = 7(1 - √x)