Posted by bryan on .
Simplify
1) (5t)(5t)^3
My answer: 5t^15
Write the number without exponents
2) 8.78x10^5
My answer: 878,000,000
Multiply.
3) (x+9)^2
My answer: 9x^18

math check 
Reiny,
no, on all three
(5t)(5t)^3
= (5t)^4
= 625t^4
8.78x10^5
= 8.78x100000
= 878000
(x+9)^2
= (x+9)(x+9)
= x^2 + 9x + 9x + 81
= x^2 + 18x + 81