Question

Rekha has 15 square colour papers of sizes 10cm,11cm,12cm,......,24cm.how much area can be decorated with these colour papers?

Answer 1

Answer:

4615cm^2

Step-by-step explanation:

Here there are square papers so area is a^2

So area=10^2+11^2+12^2+... +24^2

Formula for sum of square of natural numbers 1^2+2^2+...+n^2=(n*(n+1)*(2n+1)) /6......(1)

So here calculated area written as area=(1^2+2^2+...+24^2)-(1^2+2^2+..+9^2)

Sub n=24 in (1) equation, 1^2+2^2+..+24^2=(24*25*49) /6=4900

Sub n=9 in (1) equation,

1^2+2^2+..+9^2=(9*10*19) /6=285

So area=4900-285=4615 cm^2

Answer 2

Step-by-step explanation:

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