Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $1+9r^2 + 81r^4= 256$ and $1 + 3r + 9r^2 = 32$, then find the value of $1-3r +9r^2.$

Options:

8

4

16

12

Correct Answer:

8

Explanation:

If $1+9r^2 + 81r^4= 256$

$1 + 3r + 9r^2 = 32$,

then find the value of $1-3r +9r^2.$

We know that,

x4 + x2y2 + y4 = (x– xy + y2) (x2 + xy + y2)

then the value of $1-3r +9r^2$ = \(\frac{256}{32}\) = 8