Given expression = (11.98)² + (0.02)² + 11.98 x x.For the given expression to be a perfect square, we must have11.98 x x = 2 x 11.98 x 0.02 or x = 0.04
We have to find, the value of 4/7 of 560 - 5/8 of 400.4/7 x 560 - 5/8 x 400 = (4 x 80) - (5 x 50) = 320 - 250 = 70Hence, four-seventh of 560 is greater than five-eighth of 400 by 70.