ICSEClass XMathematicsRatio And Proportion03 Mark2025 Hard

QQuestion

Using properties of proportion, find x:

\frac{6\mathrm{x}^2+3\mathrm{x}-5}{3\mathrm{x}-5}=\frac{9\mathrm{x}^2+2\mathrm{x}+5}{2\mathrm{x}+5}, x ≠ 0.

Exam-ready answer 03 Mark

Answer

Given:

\frac{6\mathrm{x}^2+3\mathrm{x}-5}{3\mathrm{x}-5}=\frac{9\mathrm{x}^2+2\mathrm{x}+5}{2\mathrm{x}+5}

Applying componendo and dividendo:

\frac{(6\mathrm{x}^2+3\mathrm{x}-5)+(3\mathrm{x}-5)}{(6\mathrm{x}^2+3\mathrm{x}-5)-(3\mathrm{x}-5)}=\frac{(9\mathrm{x}^2+2\mathrm{x}+5)+(2\mathrm{x}+5)}{(9\mathrm{x}^2+2\mathrm{x}+5)-(2\mathrm{x}+5)} \frac{6\mathrm{x}^2+6\mathrm{x}-10}{6\mathrm{x}^2}=\frac{9\mathrm{x}^2+4\mathrm{x}+10}{9\mathrm{x}^2}

Since x ≠ 0:

\frac{6\mathrm{x}^2+6\mathrm{x}-10}{6}=\frac{9\mathrm{x}^2+4\mathrm{x}+10}{9}

⇒ 9(6x² + 6x − 10) = 6(9x² + 4x + 10)

⇒ 54x² + 54x − 90 = 54x² + 24x + 60

⇒ 30x = 150

⇒ x = 5

Was this answer helpful?