Question

a-b=5,ab=4,求3a^2+3b^2和(a+b)^2的值

Answer 1

因为a-b=5,ab=4,所以(a-b)^2+2ab=a^2+b^2=33,所以3a^2+3b^2=3(a^2+b^2)=3*33=99,(a+b)^2=a^2+b^2+2ab=33+2*4=41