√2 + √8 = √x
√2 + √(4*2) = √x
√2 + 2√2 = √x
3√2 = √x
square both sides
18 = x
√2 + √(4*2) = √x
√2 + 2√2 = √x
3√2 = √x
square both sides
18 = x
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Come on, x is the variable of this equation. All you have to do is find x. I am gonna do it by calculating the square of both sides of this equation:
(√2 + √8)² = (√x)² = x
√2² + 2*√2*√8 + √8² = x
x = 2 + 2*√(2*8) + 8
x = 10 + 2*√16 = 10 + 2*4 = 10 + 8 = 18
x = 18
(√2 + √8)² = (√x)² = x
√2² + 2*√2*√8 + √8² = x
x = 2 + 2*√(2*8) + 8
x = 10 + 2*√16 = 10 + 2*4 = 10 + 8 = 18
x = 18