Chapter 4
Exploring Algebraic Identities
CBSE Class 9
Mathematics Solutions
Educart Mathematics class Class 9 NCERT Exemplar cover
Question:

Algebra tiles can be used to represent products and find factors.
(A) Figure out the product of x+2x + 2 and x+3x + 3 using algebra tiles.
(B) Lay out algebra tiles for x2+11x+30x^{2} + 11x + 30 in such a way that you will see its factors.                    [Page No. 79]

Answer: Verified

(A) (x+2)(x+3)(x + 2)(x + 3)

Arrange algebra tiles to form a rectangle with sides (x+2)(x + 2) and (x+3)(x + 3).

1x21x^2-tile

5x-tiles (2 along one side and 3 along the other)

6 unit tiles arranged in a 2×32 \times 3 block

The total area is x2+5x+6x^2 + 5x + 6.

Hence, (x+2)(x+3)=x2+5x+6(x + 2)(x + 3) = x^2 + 5x + 6.

(B) To factor the expression, split 11x11x into two terms whose coefficients add to 11 and multiply to 30.

5+6=11,5×6=305 + 6 = 11, 5 \times 6 = 30.

Thus, x2+11x+30=x2+5x+6x+30x^2 + 11x + 30 = x^2 + 5x + 6x + 30.

Using algebra tiles, arrange:

1x21x^2-tile

11 xx-tiles (5 on one side and 6 on the other) 
30 unit tiles in a 5×65 \times 6 rectangle

The completed rectangle has dimensions (x+5)(x + 5) and (x+6)(x + 6).

Therefore, x2+11x+30=(x+5)(x+6)x^2 + 11x + 30 = (x + 5)(x + 6).

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