Question

if a-b+c=7 and a²+b²+c²=19 , then what is the value of ca-ab-bc​

Answer 1

Step-by-step explanation:

(a+b+c)2=a2+b2+c2+2ab+2bc+2ca a2+b2+c2= (a+b+c)2-2ab-2bc-2ca a2+b2+c2= (7)2-2(ab+bc+ca) a2+b2+c2= (7)2-2(20) a2+b2+c2= 49-40 a2+b2+c2= 9