Question

(b) Evaluate (2x-5y)(3x+7y)(8x-9y)

Answer 1

Can you imitate the case of identity (x+a)(x+b)=x2+x(a+b)+ab, and get a similar expression for the product (x+a)(x+b)(x+c)?

Solution:

We have, (x+a)(x+b)=x2+x(a+b)+ab.

Thus, (x+a)(x+b)(x+c)=[x2+x(a+b)+ab](x+c)

=(x)*[x2+x(a+b)+ab]+c*[x2+x(a+b)+ab]

=x3+x2(a+b)+xab+cx2+xc(a+b)+abc

= x3+x2a+x2b+xab+cx2+xca+cxb+abc

= x3+x2(a+b+c)+x(ca+cb+ab)+abc

Answer 2

Answer:

48x³-62x²y-271xy²-325y³

Step-by-step explanation:

(2x-5y)(3x+7y)(8x-9y)

{6x²+14xy-15xy-35y²}(8x-9y)

(6x²-xy-35y²)(8x-9y)

48x³-54x²y-8x²y+9xy²-280xy²-325y³

48x³-62x²y-271xy²-325y³