ICSEClass XMathematicsRatio And Proportion03 Mark2023 Easy

QQuestion

Using componendo and dividendo, solve for x:

\frac{\sqrt{2x+2}+\sqrt{2x-1}}{\sqrt{2x+2}-\sqrt{2x-1}} = 3

Exam-ready answer 03 Mark

Answer

Given:

\frac{\sqrt{2x+2}+\sqrt{2x-1}}{\sqrt{2x+2}-\sqrt{2x-1}}=3

Applying componendo and dividendo:

\frac{(\sqrt{2x+2}+\sqrt{2x-1})+(\sqrt{2x+2}-\sqrt{2x-1})}{(\sqrt{2x+2}+\sqrt{2x-1})-(\sqrt{2x+2}-\sqrt{2x-1})}=\frac{3+1}{3-1}

\frac{2\sqrt{2x+2}}{2\sqrt{2x-1}}=\frac{4}{2}

\frac{\sqrt{2x+2}}{\sqrt{2x-1}}=2

⇒ √(2x + 2) = 2√(2x − 1)

Squaring both sides:

⇒ 2x + 2 = 4(2x − 1)

⇒ 2x + 2 = 8x − 4

⇒ 8x − 2x = 2 + 4

⇒ 6x = 6

⇒ x = 1

Therefore, x = 1.

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