Visitor

2016-06-09 12:02:54

#1

If a, b and c are positiv integers then

(a+c)(3a+2b+3c) = ?

(a+c)(3a+2b+3c) = ?

Visitor

2016-06-09 12:16:18

#2

(1) a + b + c = 18

(2) 2a + b + 2c = 25

__+_______________________

(a + b + c) + (2a + b + 2c) = 18 + 25

3a + 2b + 3c = 43

And then

(3) a + b + c = 18

(4) 2a + b + 2c = 25

__-_______________________

(2a + b + 2c) - (a + b + c) = 25 - 18

a + c = 7

And then, at the end we have:

(a+c)(3a+2b+3c) = 7 x 43 = 321

(2) 2a + b + 2c = 25

(a + b + c) + (2a + b + 2c) = 18 + 25

3a + 2b + 3c = 43

And then

(3) a + b + c = 18

(4) 2a + b + 2c = 25

(2a + b + 2c) - (a + b + c) = 25 - 18

a + c = 7

And then, at the end we have:

(a+c)(3a+2b+3c) = 7 x 43 = 321

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