If a + b + c = 10 and ab+ bc+ ca = 30, then the value of $a^2 + b^2 + c^2 $ is : |
40 38 30 25 |
40 |
If a + b + c = 10 ab+ bc+ ca = 30, then 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 = 10 ab = 30, then the value of $a^2 + b^2$ = ? ( a + b )2 = a2 + b2 + 2ab ( 10 )2 = a2 + b2 + 2(30) 100 = a2 + b2 + 60 a2 + b2 = 100 - 60 = 40 |