Algebraic identities

If a+b=7, ab = 10, find a² + b²

• 28

• 29

• 30

• 27

Use identity to find , (x-6)(x-19)

• x² - 25x +114

• x² - 25x -114

• x² + 25x +114

• x² + 25x -114

 $If\ x^2\ +\ \frac{1}{x^2}\ =\ 18,\ find\ x\ -\ \frac{1}{x}$  

• 4

• -4

•  $+-4$  

• 16

If area of the triangle is 24 ( x²yz + xy²z + xyz²) and its length is 8xyz, then its breadth is ?

• 3(x + y + z)

• 3xyz

• 3(x + y - z)

• none

Using identity find 201 x 199

• 3000

• 3999

• 39999

• 31111

Find 87² - 13²

• 7200

• 7300

• 7400

• 7500

Find (2l – 3m + 4n)²

• 4l² - 9m² + 16n² – 12lm + 24mn + 16nl

• 4l² + 9m² + 16n² + 12lm – 24mn + 16nl

• 4l² + 9m² + 16n² – 12lm + 24mn + 16nl

• 4l² + 9m² + 16n² – 12lm – 24mn + 16nl

Find (2x + 3y + 5z)²

• 4x² + 9y² + 25z² + 18xy + 30yz + 20zx

• 4x² + 9y² + 25z² + 12xy + 35yz + 20zx

• 4x² + 9y² + 25z² + 12xy + 30yz + 20zx

• 4x² + 9y² + 25z² + 12xy + 30yz + 24zx