Question

If a + b = 7 and a 2 + b 2 = 29, then find the value of ab.

Answer 1

$\huge\mathfrak\blue{Answer:}$

Identity Used:

• ${(a + b)}^{2} = {a}^{2} + {b}^{2} + 2ab$ ------(1)

Given:

• $a + b = 7$
• ${a}^{2} + {b}^{2} = 29$ ------- (2)

To Find:

• The value of ab from the information given above

Solution:

Since it is Given that

$a + b = 7$

Squaring both sides we get

=> ${(a + b)}^{2} = {(7)}^{2}$

Using equation (1)

=> ${a}^{2} + {b}^{2} + 2ab = 49$ -----(3)

Using equation (2) in equation (3)

=> $29 + 2ab = 49$

=> $2ab = 20$

=> $ab = 10$

Hence the value of ab is 10

Answer 2

answer:

explanation:

(a+b)^2 - 2ab = a^2 + b^2

(7)^2 - 2ab = 29

49 - 2ab = 29

-2ab = 29 - 49

-2ab = - 20

2ab = 20

ab = 20÷2

ab = 10

hope it will help you