Question

If a : b = 2 : 1, the value of (7a + 4b) : (5a – 2b) is ______.

पर्याय

• 9 : 4

• 4 : 9

• 11 : 3

• 3 : 11

Answer 1

If a : b = 2 : 1, the value of (7a + 4b) : (5a – 2b) is 9 : 4.

Explanation:

Given a : b = 2 : 1

${\displaystyle \Rightarrow \frac{a}{b}=\frac{2}{1}}$  ...(1)

∴ ${\displaystyle \frac{7a+4b}{5a-2b}=\frac{7a+4\left(\frac{a}{2}\right)}{5a-2\left(\frac{a}{2}\right)}}$

= ${\displaystyle \frac{7a+2a}{5a-a}}$

= ${\displaystyle \frac{9a}{4a}}$

= ${\displaystyle \frac{9}{4}}$

= 9 : 4