Question

Ex
. Expand the following using suitable
identities.
a) (x + 13)(x + 20) b) (x + 30)(x + 3
c) (x – 7)(x – 7) d) (x + 1)(x -1​

Answer 1

Answer:

(a) $\textrm{x}^2 + 33\textrm{x} + 260$

(b) $\textrm{x}^2 + 33\textrm{x} + 90$

(c) $\textrm{x}^2 - 14\textrm{x} + 49$

(d) $\textrm{x}^2 - 1$

Step-by-step explanation:

For all four cases use the fact that

$(x + a) (x + b) = x^2 + (ax + bx) + ab \textrm { where a and b are constants}$

For (c) use the fact
$(x - a)(x-a) = x^2 - 2ax + a^2 \textrm{ where a is a constant}$

For (d) use the special fact
$(x+a)(x-a) = x^2 - a^2$