If a + b = -8 , and b + c = 3, and a + c = 5. Then what is a times b times c ?

Guest Aug 10, 2020

#1**0 **

Solve the following system:

{a + b = -8 | (equation 1)

b + c = 3 | (equation 2)

a + c = 5 | (equation 3)

Subtract equation 1 from equation 3:

{a + b+0 c = -8 | (equation 1)

0 a+b + c = 3 | (equation 2)

0 a - b + c = 13 | (equation 3)

Add equation 2 to equation 3:

{a + b+0 c = -8 | (equation 1)

0 a+b + c = 3 | (equation 2)

0 a+0 b+2 c = 16 | (equation 3)

Divide equation 3 by 2:

{a + b+0 c = -8 | (equation 1)

0 a+b + c = 3 | (equation 2)

0 a+0 b+c = 8 | (equation 3)

Subtract equation 3 from equation 2:

{a + b+0 c = -8 | (equation 1)

0 a+b+0 c = -5 | (equation 2)

0 a+0 b+c = 8 | (equation 3)

Subtract equation 2 from equation 1:

{a+0 b+0 c = -3 | (equation 1)

0 a+b+0 c = -5 | (equation 2)

0 a+0 b+c = 8 | (equation 3)

Collect results:

**a = -3, b = -5, c = 8 =-3 x - 5 x 8 == 120**

Guest Aug 10, 2020