Question

Fill in the blank to make the expression a perfect square.. 81x^4-___+25

Answer 1

90x^2

Answer 2

can you show step by step?

Answer 3

it's pretty hard but ill try...firstyou have 81x^4 + ___ + 25

imagine it to be ax^2 + bx + c

ax^2 is the square of the first term in the square of the binomial right?

so 81x^4 is the square of 9x^2...that's the first term of the binomial

c is the square of the second term in the binomial. so 25 is the square of 5..

so your binomial is (9x^2+5)^2

the middle term can be solved by twice the product of 9x^2 and 5 which is 90x^2...did you get it?

Answer 4

thanks