If ( a + b + c) = 7 and ab + bc + ca = 12, find the value of $a^2 +b^2 +c^2$.
Answer & explanation
Correct answer: option 4
If ( a + b + c) = 7
ab + bc + ca = 12
find the value of $a^2 +b^2 +c^2$
If the number of equations are less than the number of variables then we can put the extra variables according to our choice =
So here two equations given and three variables are present so put c = 0
If ( a + b) = 7
ab = 12
find the value of $a^2 +b^2 $ = ?
( a + b )2 = a2 + b2 + 2ab
( 7)2 = a2 + b2 + 2(12)
49 = a2 + b2 + 24
a2 + b2 = 25