Question

If a + b + c = 29 and a square + b square + c square = 791, find ab+ bc + ca​

Answer 1

Answer:

(a+b+c) ^2=a^2+b^2+c^2+2(ab+bc+ca)

(29) ^2=791+2(ab+bc+ca)

841=791+2(ab+bc+ca)

841-791=2(ab+bc+ca)

50=2(ab+bc+ca)

50/2=ab+bc+ca

25=ab+bc+ca

Answer 2

Step-by-step explanation:

given - a+b+c = 29

a^2+b^2+c^2 = 791

to find - ab+bc+ca

solution - (a+b+c)^2 = a^2+b^2+c^2+2ab+2bc+2ac

(29)^2 =791 + 2(ab+bc+ac)

841 =791 +2(ab+bc+ac)

841-791 = 2(ab+bc+ac)

50 = 2(ab+bc+ac)

25= ab+bc+ac

thus , ab+bc+ac = 25