Question

If 9, x, x and 49 are in proportion, find the value of x.

Please give the answer fast. It is urgent.

Plz plz plz

Answer 1

Hello!

$\dfrac{\sf 9}{\sf x} = \dfrac{\sf x}{\sf 49}$

⇒ $\sf x^{2} = \sf 9\:x\:49$

⇒ $\sf x^{2} = 441$

⇒ $\sf x = \sqrt{441}$ ⇒ $\sf x$ = ± $\bf{21}$

Cheers!

Answer 2

The value of x to make the elements in proportion are 21 and -21

1) The given 4 numbers are in proportion. Hence, the ratio of first and second element would be equal to ratio of third and fourth element.

2) From the definition : $\frac{9}{x} = \frac{x}{49}$

3) Cross multiplying, both the sides gives x² = 9*49

4) Hence, x = 3*7 = 21 or -21