Class 10 Maths | Quadratic Equations Exe 4.3 Q 2  | CBSE | NCERT | Full Explanation in Easy Language - video Dailymotion

Class 10 Maths | Quadratic Equations Exe 4.3 Q 2  | CBSE | NCERT | Full Explanation in Easy Language

Transcript

00:00In this video, I will teach you how to find the value of k, the value of k. Find the value of k,

00:10each of the following quadratic equations so that they have two equal roots. Now in this b

00:17square minus 4ac is equal to 0, then they have equal root. Now from the first equation we have

00:252x square plus kx plus 3 is equal to 0. This is given. Now as per the sum, it is given that

00:38the following quadratic equation so that they have two equal roots, two equal roots. So we have

00:45b square minus 4ac is equal to what? b is equal to k. So k square minus 4 into a, a is equal to what?

00:582 into c, c is equal to 3. So we have b square minus 4 is equal to what? 0. So we have 0 is equal to,

01:08we have 0 is equal to k square minus 3 into 2, 6. 3 into, 3 into 2, 6. 6 into 4, 24.

01:27Okay. So we have 24 plus 24. Okay. Why? Because when it changes position, it becomes positive. Plus

01:3524 is equal to 24, 24 is equal to 24. Now what is the factor of 24? 24 is equal to what? 24. This is for

01:53the person who do not understand maths. Okay. Otherwise, you know that 2, 12, then 2, 6, then 2,

02:043, then 3, 1. So we have 2 into 2. We have 2 into 2. So 2 square into 2 into 3, that is 6.

02:202 square into 6. If I have to find, if I have to find the root of k square, the root of k square is

02:29equal to k, and the root of 2 square is equal to 2, and the root of 6 is equal to root 6.

02:36And this can be plus or minus. So our answer is 2 root 6 plus or minus 2 root 6. This question can be

02:45asked for basic as well as standard. Okay. Now, the second one. Second is kx into 2x minus 3 plus 6.

02:54So our question is kx into x minus 2. Okay. So we have kx into x minus 2.

03:10Our question is 2 plus plus 6 is equal to 0. Plus 6 plus 6 is equal to 0. Multiplying kx into bracket. We have

03:32kx into kx into kx into 2. It is 2 times k. Okay. Now, b square minus 4ac. So what comparing with

03:54a square is kx, b square minus c is equal to b square minus 4ac,

03:59equals 0, spirit, cars is equal to six equal to 10. Plus 4ac is equal to what? We have to calculate b square

04:16minus 4 AC. Okay one minute. B square minus 4 AC is equal to minus 2K square minus 4

04:42into K into 6. That is minus 4 into minus 2 into 2 minus 2 that is 4 K square minus 3 to 3 for the 24 K.

05:01Okay and it is equal to 0. So we have 0 is equal to 4 K bracket K minus 6. Therefore we have

05:194 K is equal to 0 or K minus 6 is equal to 0. Now 4 is equal to 0. No 4 is not equal to 0.

05:32We have 4 is not equal to 0. Therefore K is equal to 0 or we have K is equal to 6. So we have two

05:44values for this K 0 and 6. Okay. If you are new to my youtube channel please subscribe my channel

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