Quantitative Aptitude?If ap =bq =cr and b^2 =ac the value of q(p + r)/...
Solution:
Given, ap = bq = cr and b^2 = ac
We need to find the value of q(p + r)/pr
Let's try to simplify the given expressions first:
ap = bq = cr
We can write,
a/b = c/r = p/q = k (let's say)
So, ap = bq = cr = k^2
Now, b^2 = ac
We know, a/b = c/r
So, a/c = b/r = 1/k
b^2 = ac
b^2 = a*c*(1/k^2)
b^2 = k^2*(1/k^2)
b^4 = 1
b = ±1 (since b cannot be 0 as it will make ac = 0, which is not possible)
Now, let's substitute the values of a/b and b^2/ac in q(p+r)/pr
q(p+r)/pr = q/p + q/r
We know, a/b = c/r = p/q
So, p = q(a/b) and r = q(c/b)
Substituting these values in the above expression, we get:
q(p+r)/pr = q/p + q/r
= q/(q*a/b) + q/(q*c/b)
= b/a + b/c
= (bc+ab)/(ac)
= b(a+c)/(ac)
Now, we also know that b^2 = ac
So, a = b^2/c
Substituting this value in the above expression, we get:
q(p+r)/pr = b(a+c)/(ac)
= b(b^2/c + c)/(c*b^2/c)
= (b^3 + bc)/(b^2)
= b + c/b
= ±1 + c/b
We know that b cannot be 0 and we have already proved that b can only be ±1. So, substituting these values, we get:
q(p+r)/pr = ±1 + c/b
= ±1 ± c
= ±1 (since c cannot be 0 as it will make b^2 = ac = 0, which is not possible)
Therefore, the value of q(p+r)/pr is ±1.
Answer: Option 1 or -1.
Quantitative Aptitude?If ap =bq =cr and b^2 =ac the value of q(p + r)/...
give options