Rectangle 7768

The base of a cuboid is a rectangle. The ratio of its length to width is 3:2. The length of the rectangle of the base is in the ratio of 4:5 to the height of the block. The sum of the lengths of all the edges of the block is 2.8m. Find:
a) the surface of the cuboid in cm2
b) volume in dm3

Correct answer:

S =  50688 cm2
V =  737280 cm3

Step-by-step explanation:

a=3/2 b a=4/5 c a+b+c=2.8 100  2a3b=0 5a4c=0 a+b+c=280  Pivot:Row1Row2 5a4c=0 2a3b=0 a+b+c=280  Row252 Row1Row2 5a4c=0 3b+1.6c=0 a+b+c=280  Row351 Row1Row3 5a4c=0 3b+1.6c=0 b+1.8c=280  Row331 Row2Row3 5a4c=0 3b+1.6c=0 2.333c=280  c=2.33333333280=120 b=301.6c=301.6 120=64 a=50+4c=50+4 120=96  a=96 b=64 c=120  S=2 (a b+b c+c a)=2 (96 64+64 120+120 96)=50688 cm2
V=a b c=96 64 120=737280 cm3

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