Question

How do you find the product of `(9 - 7x)^2`?

Answer 1

`81-126x+49x^2`

Explanation:

`"note "(9-7x)^2=(9-7x)(9-7x)`

`"each term in the second factor must be multiplied by"`
`"each term in the first factor"`

`rArr(color(red)(9-7x))(9-7x)`

`=color(red)(9)(9-7x)color(red)(-7x)(9-7x)`

`=(color(red)(9)xx9)+(color(red)(9)xx-7x)+(color(red)(-7x)xx9)+(color(red)(-7x)xx-7x)`

`=81color(blue)(-63x)color(blue)(-63x)+49x^2`

`=81-126x+49x^2`