Math
posted by Mimi on .
Mutliply.
(9t²  t 7)(4t²+9t1)
AND
Find the product.
(5a+2)³

Multiply:
(9t²  t 7)(4t²+9t1)
You can do a long multiplication, with the appropriate terms in the same columns, just like the multiplication of multidigit numbers.
Alternatively, you can multiply visually, looking for highest to lowest terms:
t^4: 9*4 =36
t^3: 9*9+4(1)=77
t^2: 9(1)+(1)(9)+(7)(4)=46
t: (7)(9)+(1)(1)=62
1: (7)(1) = 7
So the product is:
36t^4+77t^346t^262t+7
Quick check:
put t=1, so calculate the sum of coefficients of each factor:
(9t²  t 7)(4t²+9t1)
=(917)(4+91)
=1*12
=12
Sum of coefficients of product
=36+774662+7
=12
checks.