i)Let the breadth be x m and the length will be 2x+1 m.
Area = l × b
Area = x(2x+1) = 528
2x² + x - 528 = 0
2x² + 33x - 32x - 528 = 0
⇒2x(x - 16) + 33(x - 16) = 0
⇒(2x + 33)(x - 16) = 0
⇒x = 16, -33/2
Breadth = 16m and length = 33m
ii)Let one number be x then the next number will be x+1
x(x+1) = 306
⇒x² + x - 306 = 0
⇒x² + 18x - 17x - 306 = 0
⇒x(x + 18) - 17(x + 18) = 0
⇒(x + 18)(x - 17) = 0
⇒x = 17, -18
The numbers are 17 and 18.
iii)Let Rohan's present age = x yrs.
Then his mother's present age = x + 26 yrs
After 3 yrs
Rohan's age = x + 3 yrs
His mother's age = x + 29 yrs
(x + 3)(x + 29) = 360
⇒x² + 32x + 87 - 360 = 0
⇒x² + 32x - 273 = 0
⇒x² + 39x - 7x - 273 = 0
⇒x(x + 39) - 7(x + 39) = 0
⇒(x + 39)(x - 7) = 0
⇒x = 7, -39
So, Rohan's present age = 7 yrs.
iv)Let the speed of the train = x km/hr
480/(x - 8) - 480/x = 3
⇒480x - 480x + 3840 = 3x(x - 8)
⇒3x² - 24x - 3840 = 0
⇒x² - 8x - 1280 = 0
⇒x² - 40x + 32x - 1280 = 0
⇒x(x - 40) + 32(x - 40) = 0
⇒(x + 32)(x - 40) = 0
⇒x = 40, -32
The speed of the train is 40 km/hr.