Look! It's A Square!

Geometry Level 1

1 2 + 1 2 + 1 2 + 1 2 + 2 2 + 2 2 + 2 2 + 3 2 = ? \Large 1^2 + 1^2 + 1^2 + 1^2 + 2^2 + 2^2 + 2^2 + 3^2 = \, ?

4 2 4^2 5 2 5^2 6 2 6^2 7 2 7^2

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4 solutions

Oli Hohman
Mar 24, 2016

The image is extremely helpful in visualizing what's happening. The side length of the biggest inner square is 3 and the next largest inner square's side length is 2. This means the base of the entire square is 5. The area of a square is, not incidentally, the side length squared. So, the answer is 5^2.

More algebraically, you have 4(1)^2 + 3(2)^2 + 3^2 = 4+12+9 = 25 = 5^2

Yes! This is the intended solution. Thank you :)

Chung Kevin - 5 years, 2 months ago
Mehul Arora
Mar 20, 2016

1 2 + 1 2 + 1 2 + 1 2 + 2 2 + 2 2 + 2 2 + 3 2 = 4 × 1 2 + 3 × 2 2 + 9 = 25 = 5 2 1^2+1^2 + 1^2 + 1^2 + 2^2 + 2^2 + 2^2 + 3^2 \\ = 4 \times 1^2 + 3 \times 2^2 + 9 = 25 \\ = 5^2 _{\square}

Seeing the image,it can be answered in seconds!

Anik Mandal - 5 years, 2 months ago

why use multiplication Operator? in this Question we give only Add operator

Asif Khan - 5 years, 2 months ago

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I used multiplication to make the solution easier, I guess. It's not a necessity though.

Mehul Arora - 5 years, 2 months ago

It's called factoring. There are 4 (1^2) terms, 3 (2^2) terms, and 1 (3^2) term, so it can be rewritten as such.

Oli Hohman - 5 years, 2 months ago

It should read 4(1)^2, not 3(1)^2.

Oli Hohman - 5 years, 2 months ago

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Oops! Sorry. Thanks, edited.

Mehul Arora - 5 years, 2 months ago
Santiago Hincapie
Mar 25, 2016

1 2 + 1 2 + 1 2 + 1 2 + 2 2 + 2 2 + 2 2 + 3 2 = 2 ( 2 × 1 2 ) + 2 × 2 2 + 2 2 + 3 2 = 2 2 + 2 ( 2 × 1 2 + 2 2 ) + 3 2 = 2 2 + 2 ( 2 ) ( 1 2 + 2 ) + 3 2 = 2 2 + 2 ( 2 ) ( 3 ) + 3 2 = ( 3 + 2 ) 2 = 5 2 = 25 1^2+1^2 + 1^2 + 1^2 + 2^2 + 2^2 + 2^2 + 3^2 \\ = 2(2 \times 1^2) + 2 \times 2^2 + 2^2 + 3^2 \\ = 2^2 + 2(2 \times 1^2 + 2^2) + 3^2 \\ = 2^2+2(2)(1^2+2)+3^2\\ = 2^2+2(2)(3)+3^2=(3+2)^2=5^2=25

Harish Ghunawat
Mar 20, 2016

Saw the image :)

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