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Mathematics

Using properties of proportion, find the value of ‘x’:

6x2+3x53x5=9x2+2x+52x+5  x0\dfrac{6x^{2} + 3x - 5}{3x - 5} = \dfrac{9x^{2} + 2x + 5}{2x + 5} \; x \neq 0

Ratio Proportion

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Answer

Given,

6x2+3x53x5=9x2+2x+52x+5\Rightarrow \dfrac{6x^{2} + 3x - 5}{3x - 5} = \dfrac{9x^{2} + 2x + 5}{2x + 5}

Applying componendo and dividendo,

6x2+3x5+(3x5)6x2+3x5(3x5)=9x2+2x+5+(2x+5)9x2+2x+5(2x+5)6x2+3x5+3x56x2+3x53x+5=9x2+2x+5+2x+59x2+2x+52x56x2+6x106x2=9x2+4x+109x26x2+6x106=9x2+4x+1099×(6x2+6x10)=6×(9x2+4x+10)54x2+54x90=54x2+24x+6054x2+54x9054x224x60=054x254x2+54x24x9060=030x150=030x=150x=15030x=5.\Rightarrow \dfrac{6x^{2} + 3x - 5 + (3x - 5)}{6x^{2} + 3x - 5 -(3x - 5)} = \dfrac{9x^{2} + 2x + 5 + (2x + 5)}{9x^{2} + 2x + 5 - (2x + 5)} \\[1em] \Rightarrow \dfrac{6x^{2} + 3x - 5 + 3x - 5}{6x^{2} + 3x - 5 - 3x + 5} = \dfrac{9x^{2} + 2x + 5 + 2x + 5}{9x^{2} + 2x + 5 - 2x - 5} \\[1em] \Rightarrow \dfrac{6x^{2} + 6x - 10}{6x^{2}} = \dfrac{9x^{2} + 4x + 10}{9x^{2}} \\[1em] \Rightarrow \dfrac{6x^{2} + 6x - 10}{6} = \dfrac{9x^{2} + 4x + 10}{9} \\[1em] \Rightarrow 9 \times (6x^{2} + 6x - 10) = 6 \times (9x^{2} + 4x + 10) \\[1em] \Rightarrow 54x^{2} + 54x - 90 = 54x^{2} + 24x + 60 \\[1em] \Rightarrow 54x^{2} + 54x - 90 - 54x^{2} - 24x - 60 = 0 \\[1em] \Rightarrow 54x^{2} - 54x^{2} + 54x - 24x - 90 - 60 = 0 \\[1em] \Rightarrow 30x - 150 = 0 \\[1em] \Rightarrow 30x = 150 \\[1em] \Rightarrow x = \dfrac{150}{30} \\[1em] \Rightarrow x = 5.

Hence, x = 5.

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