Which statements about the factors of the terms in the expression 20 a + 15 a b + 24 b are true? Select three options.
The factors common to 20a and 15ab are 1, 5, a, and b.
The factors common to 20a and 15ab are 1, 5, and a.
The factors common to 20a and 24b are 1, 2, and 4.
The GCF of the expression is ab.
The GCF of the expression is 1

please help me with this, I have a unit test review.

Following are the true statements

2. The factors common to 20a and 15ab are 1, 5, and a.

3. The factors common to 20a and 24b are 1, 2, and 4.

5. The GCF of the expression is 1

Step-by-step explanation:

Expression is  20a + 15ab + 24b

Now lets have a look at each of the options provided!

1. The factors common to 20a and 15ab are 1, 5, a, and b.

False

As you can see there is no b in 20a term only 1,5,a are common hence it is false.

2. The factors common to 20a and 15ab are 1, 5, and a.

True

The terms 20a and 15ab are divisible by 1,5,a hence it is true.

3. The factors common to 20a and 24b are 1, 2, and 4.

True

The terms 20a and 24b are divisible by 1,2,4 hence it is true

4. The GCF of the expression is ab.

False

20a + 15ab + 24b

As you can see ab is not common in all of the terms hence it cannot be greatest common factor

5. The GCF of the expression is 1

True

Factor of 20 are: 2,2,5,1

Factor of 15 are: 3,5,1

Factor of 24 are: 2,2,2,3,1

As you can see the only common factor among all the terms is 1 hence GCF is 1.

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.