Question

$xy + yz + zx = 35 \: and \: {x}^{2} + {y}^{2} + {z}^{2} = 155 \: find \: 3(x + y + z)$
VERY URGENT PLEASE SOLVE​

Answer 1

Answer:-

Given:

• xy + yz + zx = 35 -- equation (1)

• x² + y² + z² = 155 -- equation (2).

We know that,

(a + b + c)² = a² + b² + c² + 2(ab + bc + ac).

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

Putting the values from equations (1) & (2) we get,

⟹ (x + y + z)² = 155 + 2(35)

⟹ (x + y + z)² = 155 + 70

⟹ (x + y + z)² = 225

⟹ x + y + z = √225

⟹ x + y + z = ± 15

Now,

Multiply both sides by 3.

⟹ 3(x + y + z) = 3( ± 15)

⟹ 3(x + y + z) = ± 45

∴ The value of 3(x + y + z) is ± 45.

Answer 2

Refer to above attachment

Hope u helpful