Question

maths class 10 ,4.1 q 2) iv
train travels a distance of 480 km at a uniform speed if the speed had be 8 km per hour less than it would have taken 3 hours more to cover the same distance we need to find the speed of train.​

Answer 1

Answer:

40 km/hr

Step-by-step explanation:

x² - 8x - 1280 = 0

b² - 4ac = 64 + 5120 = 5184

$\sqrt{5184} = 72$

$\frac{ - b + \sqrt{{b}^{2} - 4ac}}{2a} = \frac{8 + 72}{2} = \frac{80}{2} = 40$

$\frac{ - b - \sqrt{{b}^{2} - 4ac}}{2a} = \frac{8 - 72}{2} = \frac{ - 64}{2} = - 32$

Since speed cannot be negative .

Therefore, speed is 40 km/hr.