Question

if a-b-c=4 and -ab+bc-ca=-3 find the value of a^2+b^2+c^2​

Answer 1

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

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

(a-b-c)^2=a^2+b^2+c^2-2 (a.-b+ -b.-c+ -c.a).

(4)^2=a^2+b^2+c^2-2 (-3).

16=a^2+b^2+c^2+6.

16-6=a^2+b^2+c^2.

10= a^2+b^2+c^2.