Formula for x^2+y^2

Q.

If $(a-b)=6$ and $a^2+b^2=30$, then the value of ab is equal to ____.

1. -3

2. -6

3. -2

4. -1

Q.

The value of following expression when x = 3, $x^2$ − 5x + 4 gives $(-3{)}^2$ − 5 (−3) + 4 = 9 + 15 + 4 = 28

1. True

2. False

Q.

Compute the value of ${35}^2+5^2$

1. = $1420$

2. = $1460$

3. = $1560$

4. = $1480$

Q.

If $x+x^{-1}=11$, evaluate $x^2+x^{-2}$.

1. 119
2. 120
3. 121
4. 122

Q.

Compute the value of ${19}^2+{11}^2$

1. = $482$

2. = $492$

3. = $462$

4. = $472$

Q.

Compute the value of ${12}^2+8^2$

1. $218$

2. $208$

3. $198$

4. $204$

Q. Compute the value of ${72}^2-{28}^2$.

Q.

Compute the value of $7^2+{13}^2$

1. = $225$

2. = $215$

3. = $220$

4. = $210$

Q. Use direct method to evaluate :
$(2+a)(2-a)$