Question

Simplify the expression 2 (x² – 3x) – 5 17 x – 4) – 5 and find the value when x = -3 ​

Answer 1

Answer:

$2( {x}^{2} - 3x) - 5(17x - 4) - 5 \\ x = - 3 \\ 2( {3}^{2} - 3(3)) - 5(17(3) - 4) - 5 \\ 2(9 - 9) - 5(51 - 4) - 5 \\ 0 - 5(47) - 5 \\ - 235 - 5 \\ = - 240$

Answer 2

Answer:

Now, (x+ y)3 – (x3 + y3) = (x + y) – (x + y)(x2– xy + y2)

[using identity, a3 + b3 = (a + b)(a2 -ab+ b2)] = (x+ y)[(x+ y)2 -(x2 -xy+ y2)]

= (x+ y)(x2+ y2+ 2xy- x2+ xy- y2)

[using identity, (a + b)2 = a2 + b2 + 2 ab)]

= (x + y) (3xy)

Hence, one of the factor of given polynomial is 3xy.