Question

which number should be subracted from 12;16 and 21
so bot that the resultant number are in continued
proportion​

Answer 1

Answer:

-4

Step-by-step explanation:

Let the number to be subtracted be "x".

Hence,

$(12-x):(16-x) : : (16-x):(21-x)\\\\\frac{12-x}{16-x} = \frac{16-x}{21-x} \\\\(12-x)(21-x)=(16-x)(16-x) \ \ \ \ \: ...(By \ cross \ multiplication)\\\\12\times 21 - 12x - 21x + x^2=(16-x)^2\\\\252-33x+x^2=256+x^2-32x\\\\-33x+32x-x^2+x^2=256-252\\\\-x=4\\\\x=-4$

So, -4 should be subtracted from each of the terms to get them in continued proportion.