Question

If p + q = 4 and p2 + q2 = 7, then the value of p q is​

Answer 1

Answer:

ANSWER

p + q = 4

and p

2

+ q

2

= 7

(p + q)

2

= (4)

2

= 16

⇒ p

2

+ q

2

+ 2pq = 16

⇒ 7 + 2pq = 16

⇒ 2pq = 9

pq =

2

9

Answer 2

Given :-

p + q = 4

p^2 + q^2 = 7

To Find :-

The value of p and q and pq

Solution :-

Here we know,

p + q = 4........eq( 1)

p^2 + q^2 = 7

Using identity a^2 + b^2 = ( a + b) ( a - b)

( p + q) ( p - q ) = 7

4 + ( p - q) = 7

( From eq(1) the value of p+ q= 4)

( p - q) = 7 - 4

(p - q ) = 3 .........eq( 2 )

Solve by Elimination method,

p + q = 4

p - q = 3

p - 0 = 1

p = 1........eq( 3)

Subsitute eq( 3) in eq( 1)

p + q = 4

1 + q = 4

q = 4 - 1

q = 3

Now , The value of pq

pq = 1 * 3

pq = 3

3 is your answer mate