Hey this will be really quick it’s just a true/false, pls help

Question

Which statements are true?

1. 20 is the greatest common factor of 40 and 80.
2. 64 is a perfect square.
3. x(x^2+1)=x^3+x
4. x^2-81 cannot be factored
5. 3x^3 is the GCF of 15x^4+9x^2+3
6. (x+5) is a factor of x^2-2x+15
7. (4x^2+2)(x^2-2)=4x^4-6x^2-4
8. x+3 is a factor of x^2+9
9. The product of two binomials is always a trinomial.
10. 57 is a prime number.

Answer 1

2,3 and 7 are true

all the rest are false

1. greatest common factor is 40
2. TRUE, 8 x 8 = 64
3. TRUE
4. x^2 -81 = (x-9)(x+9)
5. false
6. try dividing, it doesn't come out even, or substitute -5 for x, you don't get zero
7. TRUE, Use FOIL
8. x^2 -9 has factors of (x+3)(x-3) but x^2+9 has only imaginary factors (x+3i)(x-3i)
9. see 8. (a-b)(a+b) = a^2-b^2, It's not always a trinomial
10. 57 = 3(19) When the digits sum to a multiple of 3, it's divisible by 3, with a factor of 3 5+7 =12 =3(4)