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√ x ^ 2 - 8 = 2 x ^ 2 - 8 = 4 x ^ 2 = 12 x = + - 2 √ 3

Sq Root 12

X=2*3^(1/2) X est égal à 2 fois racine carré de 3

Square root of 12

Radice di 12

x = +/- 2V3

X = Sqrt(12)

X=2√3

Hard

7^(x²-8)^1/2 = 7² (x²-8)^1/2 = 2 x²-8 = 4 x² = 12 |x| = 12^1/2 = 2(3^1/2) x= +/- 2(3^1/2)

x²=12 ⇔x=±2√3　　Answer “⇔”は必要十分条件。 x=2√3 だけ答えるのは、 矢印が “←”　だけで誤り。

It's very tough

15

X = +- Sqrt 57

x = ±2√3

x = 2√3

?=±2*sqrt(3) => 7²=49 sqrt(x²-8)=2 x²-8=2²=4 x²=12 x=sqrt(12) x=sqrt(3*4) x=±2*sqrt(3)

7²=49 So: √(X²-8)=2 X²-8=2²=4 X²=4+8=12 X=√12 =2√3= X= ± almost 3½ (3.461 ish)

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solution: x= +/- 2√3 7^√(x²-8) = 49 = 7² => √(x²-8) = 2 | ^2 x²-8=4 |+8 x²=12=√4*3= +/- 2√3 Pr.: 7^√[(+/-2√3)²-8] = 7^√(4*3-8) = 7^(√4) = 7² =49 q.e.d.

X²-8=4 X=±2√3