Question

102. If x2 + y2 + z2 = 29 and xy + y2 + zx = 26,
then the value of x+y+z is :
(1) 9
(2) 81
(3) +9
(4) 3​

Answer 1

$\huge\sf\purple{Solution}$

Given that

x² + y² + z² = 29

xy+yz+zx = 26

Then x+ y+z=?

We can findout value of x+y+z from formula

$\huge\sf\underline{Formuala}$

(x+y+z)² = x² + y² + z² + 2xy + 2yz + 2zx

Now substuite all values in given formula

( x + y + z )² = 29+2xy+2yz+2zx

(x + y + z)²=29+2(26)

(x + y + z)²=29+52

(x+y+z)²=81

(x+y+z) = 9 or -9

Answer 2

Step-by-step explanation:

$\huge\bf\underline\green{answer}$

$\huge\sf\underline\blue{given,}$

${x}^{2} + {y}^{2} + {z}^{2} = 29$

$xy + yz + zx = 26$

$\huge\fcolorbox{black}{pink}{required formula}$

$(x + y + z) {}^{2} = {x}^{2} + {y}^{2} + {z}^{2} + 2xy + 2yz + 2zx$

$\huge\bf\underline{solution}$

substituting the values in the equation:

(x+y+z)^2 = 29+2(26)

(x+y+z)^2 = 29+52

(x+y+z)^2 = 81

(x+y+z)^2= √81

(x+y+z)^2= +9(or)-9