Question

A+B=15, B+C=7, C+A=-21A+B+C=?​

Answer 1

Ответ:

A+B  +  B+C   +  C+A = 15+7+21=43

A+B  +  B+C   +  C+A  = 2A+2B+2C=2*(A+B+C)=43​​

2*(A+B+C)=43​​

(A+B+C)=43​​/2

(A+B+C)=21,5

 

Answer 2

To find the value of A + B + C, we can solve the system of equations provided.

Given: A + B = 15 ...(1) B + C = 7 ...(2) C + A = -21 ...(3)

To solve this system, we can use substitution or elimination method. Let's use the elimination method here.

Adding equations (1) and (3), we get: (A + B) + (C + A) = 15 + (-21) 2A + B + C = -6 ...(4)

Now, subtract equation (2) from equation (4): (2A + B + C) - (B + C) = -6 - 7 2A = -13 A = -13/2 A = -6.5

Substitute the value of A into equation (1): -6.5 + B = 15 B = 15 + 6.5 B = 21.5

Substitute the values of A and B into equation (2): 21.5 + C = 7 C = 7 - 21.5 C = -14.5

Finally, we can calculate A + B + C: A + B + C = -6.5 + 21.5 + (-14.5) = -6.5 + 21.5 - 14.5 = 0.5

Therefore, A + B + C equals 0.5.