Question

If a^2+b^2+c^2=90 and a+b+c=20, then the value of ab+bc+ca is PLZ WITH A CLEAR EXPLANATION PLZ PLZ PLZ

Answer 1

Answer:

155

Step-by-step explanation:

(a²+b²+c²)+2(ab+bc+ca)=(a+b+c)²

90+2(ab+bc+ca)=(20)²

90+2(ab+bc+ca)=400

2(ab+bc+ca)=400-90=310

ab+bc+ca=310/2=155