Question

solve Evaluate using suitableIdentities. 1. (2a + 7) (2a – 7)

Answer 1

Answer:

2a−7)(2a−7)=(2a−7)

2

using identity (a−b)

2

=a

2

−2ab+b

2

(2a−7)

2

=(2a)

2

−2×2a×7+7

2

(2a−7)

2

=4a

2

−28a+49

Answer 2

Answer:

Using identity

$(x^2-y^2)=(x-y)(x+y)$

$(2a+7)(2a-7)=(4a^2-49)$

Step-by-step explanation:

In Algebra, there are different identities for solving the polynomials. Thus, one of the identities required to solve and evaluate the question is given by

using identity

$(x^{2}-y^{2}) = (x-y)(x+y)$

Given value to evaluate is (2a+7)(2a-7)

comparing it with the identity, we get

x=2a

y=7

By substituting the value of x and y in identity, we get

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

$(2a-7)(2a+7)=4a^2-49$

Thus, the value is

$(2a+7)(2a-7)=(4a^2-49)$