Question

What is the product (9t-4)(-9t
-4)

Answer 1

Combine like terms: -81t^2 + 16

Answer 2

Hey Tro2,

Lets find the product of your equation together,

The question we are encountering is : What is the product (9t-4)(-9t-4)?

Lets simplify this step by step, shall we.


`\left(9t-4\right)\left(-9t-4\right)` : Equation


`\mathrm{Distribute\:parentheses\:using}:\quad \left(a+b\right)\left(c+d\right)=ac+ad+bc+bd`.

Where :
`a=9t,\:b=-4,\:c=-9t,\:d=-4` .

This leads to
`9t\left(-9t\right)+9t\left(-4\right)-4\left(-9t\right)-4\left(-4\right)`.

Now we have to
`\mathrm{Apply\:minus-plus\:rules}`.

Where:
`-\left(-a\right)=a,\:\:\:\:+\left(-a\right)=-a`


`-9t\cdot \:9t-9t\cdot \:4+4\cdot \:9t+4\cdot \:4`


`=-81t^2+16`