Selina Solutions Class 9 Mathematics Solutions for Exercise 4(A) in Chapter 4 - Chapter 4- Expansions

Question 6 Exercise 4(A)

12.If a2-3a+1=0 and a≠0; find:

(i) 𝒂 + 1/a

$\text { (ii) } \quad a^{2}+\frac{1}{a^{2}}$

Answer:

(i)

(ii)

Video transcript

"hello student welcome to leader learning question answer video solutions my name is beljut gore and i'm your mathematics tutor so today's problem is if a square minus 3 a plus 1 is equals to 0 and a is not equals to 0 find the value of a plus 1 by 8 so students if you have remember we have done similar kind of these problems so let's get started guys so the equation is a square minus 3a plus 1 is equals to 0. now there is no way i can find a plus 1 by a like this so let me do one thing let me rearrange this so if i rearrange it in the form of like this so i will get this equation now what i'm going to do is i'm going to divide the whole equation i'm going to divide the whole equation by a so i will get a plus 1 by a which is equals to 3 so i will have this equation like this now see guys we have a plus 1 by equals to 3 now that's the value we needed to find simple now let's come to the next part the next part is a square plus 1 by a square now guys what i can do is if i go back to the previous question a plus 1 by a if i square it so if i square it so i will have a plus 1 by a whole square which can be written as a square plus 1 by a square plus 2 and a and 1 by a will get cancelled by each other we have a square plus 1 by a square now what i'm going to do is i'm going to write this part as a square plus 1 by a square only i'm going to write this 2 as a only now guys if you have remember a plus 1 by is 3 so 3 square is 9 so 9 minus 2 is equals to a square plus 1 by a square which is 7. now that's the answer to the problem thank you so much for watching the video kids if you have any questions any queries please drop down in the comment section for more fun videos subscribe to leader have a wonderful day kids "

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Exercises

Exercise 4(A)

Exercise 4(B)

Exercise 4(C)

Exercise 4(D)