## PRACTICE QUESTION FOR a PLUS b WHOLE SQUARE

(a+b)2 = a2+2ab+b2

Problem 1 :

Expand (3x + 7y)

(A) x2 + 42xy + 49y2    (B) 9x2 + 42xy + 49y2

(C) 9x2 - 42xy - 9y2

Problem 2 :

Expand (2x + 3y)²

(A)  4x²+12xy+9y²  (B)  16x²+42xy+49y²

(C)  9x²+12xy-9y²

Problem 3 :

Expand (2a + 3b)²

(A) 4a²+12ab+9b²  (B) 16a²+25ab+49b²

(C)  9a²+42ab+9b²

Problem 4 :

Expand (a + 5b)²

(A) a² + 10 ab + 25 b²  (B)  9a² + 25 ab + 16 b²

(C)  9a² +12 ab + 9 b²

Problem 5 :

Expand (3p + 5q)²

(A) 3p² + 40 pq + 25 q²   (B) p² + 30 pq + 49 q²

(C)  9p² +30 pq + 25 q²

Problem 6 :

Expand (5c + 7d)²

(A) 5c² + 35cd + 7d²  (B) 5c² - 35cd + 7d²

(C)  25c² + 70cd + 49d²

## Solutions for the Above Practice Questions

Problem 1 :

Expand (3x + 7y)

Solution :

(a + b)2 = a2 + 2 a b + b2

Here a  =  3x and b  =  7y

(3x + 7y)2  =  (3x)2 + 2(3x)(7y) + (7y)2

=  9x2+42xy+49y2

Problem 2 :

Expand (2x + 3y)²

Solution :

Here a  =  2x and b  =  3y

(2x + 3y)2  =  (2x)2+2(2x)(3y)+(3y)2

=  4x2+12xy+9y2

Problem 3 :

Expand (2a + 3b)²

Solution :

Here a  =  2a and b  =  3b

(2a + 3b) =  (2a)2 + 2 (2a)(3b) + (3b)2

=  4a2 + 12 a b + 9 b2

Problem 4 :

Expand (a + 5b)²

Solution :

Here a  =  a and b  =  5b

(a + 5b)2  =  (a)2 + 2 (a)(5b) + (5b)2

=  a2 + 10 a b + 25 b2

Problem 5 :

Expand (3p + 5q)²

Solution :

here a  =  3p and b  =  5q

(3p + 5q)2  =  (3p)2 + 2(3p)(5q) + (5q)2

=  9p2 + 30 pq + 25q2

Problem 6 :

Expand (5c + 7d)²

Solution :

here a  =  5c and b  =  7d

(5c + 7d)2  =  (5c)2 + 2(5c)(7d) + (7d)2

=  25c2 + 70 cd + 49d2

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