An increase in the speed of car by 10 km/hr saves 1 hr in a journey of

1.	An increase in the speed of car by 10 km/hr saves 1 hr in a journey of 200 k, Find the initial speed of the car.
Answer» $\huge{\underline{\underline{\mathbb{\red{Answer:-}}}}}$ Let original speed be x km/hr. ∴ Time = 72/x hr New speed = x + 10 km/hr. ∴ New time = 72/x + 10 hr Difference in time = 36 mins ∴ 72/x - 72/x + 10 = 36/60 72x + 720 – 72x/x(x + 10) = 3/5 5 × 720 = 3(x2 + 10x) 1200 = x2 + 10x x2 + 10x – 1200 = 0 x2 + 40X – 30x – 1200 = 0 x(x + 40) – 30(x + 40) = 0 (x – 30)(x + 40) = 0 ∴ x = 30 as x = - 40 is not acceptable ∴ Original speed = 30 km/hr. $please mark me brainlist ✔️$

An increase in the speed of car by 10 km/hr saves 1 hr in a journey of 200 k, Find the initial speed of the car.

Answer»

$\huge{\underline{\underline{\mathbb{\red{Answer:-}}}}}$

Let original speed be x km/hr.

∴ Time = 72/x hr

New speed = x + 10 km/hr.

∴ New time = 72/x + 10 hr

Difference in time = 36 mins

∴ 72/x - 72/x + 10 = 36/60

72x + 720 – 72x/x(x + 10) = 3/5

5 × 720 = 3(x2 + 10x)

1200 = x2 + 10x

x2 + 10x – 1200 = 0

x2 + 40X – 30x – 1200 = 0

x(x + 40) – 30(x + 40) = 0

(x – 30)(x + 40) = 0

∴ x = 30

as x = - 40 is not acceptable

∴ Original speed = 30 km/hr.

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