If a : b = 2 : 1, the value of (7a + 4b) : (5a - 2b) is :
9 : 4
4 : 9
11 : 3
3 : 11
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Given,
⇒ab=21⇒a=2b.\Rightarrow \dfrac{a}{b} = \dfrac{2}{1} \Rightarrow a = 2b.⇒ba=12⇒a=2b.
Substituting value of a in (7a + 4b) : (5a - 2b), we get :
⇒7a+4b5a−2b⇒7×2b+4b5×2b−2b⇒14b+4b10b−2b⇒18b8b⇒94⇒9:4.\Rightarrow \dfrac{7a + 4b}{5a - 2b} \\[1em] \Rightarrow \dfrac{7 \times 2b + 4b}{5 \times 2b - 2b} \\[1em] \Rightarrow \dfrac{14b + 4b}{10b - 2b} \\[1em] \Rightarrow \dfrac{18b}{8b} \\[1em] \Rightarrow \dfrac{9}{4} \\[1em] \Rightarrow 9 : 4.⇒5a−2b7a+4b⇒5×2b−2b7×2b+4b⇒10b−2b14b+4b⇒8b18b⇒49⇒9:4.
Hence, Option 1 is the correct option.
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If (3x - 9) : (5x + 4) is the triplicate ratio of 3 : 4, find the value of x.
If x, 2, 10 and y are in proportion, the values of x and y are respectively :
0.2 and 0.25
0.2 and 50
0.4 and 50
0.4 and 25
If x : y = y : z, then x2 : y2 is :
1 : x
x : y
x : z
z : x
The mean proportion between 3+22 and 3−223 + 2\sqrt{2} \text{ and } 3 - 2\sqrt{2}3+22 and 3−22 is :
1
-1
222\sqrt{2}22
3
