Question

22.....................

Answer 1

`a=11,b=7`

Explanation:

The given equation is

`(5x^7y^2)(-4x^4y^5)=-20x^ay^b`

Recall that
`a^m* a^n =a^(m+n)`

We simplify the left hand side to obtain;

`-20x^(7+4)y^(2+5)=-20x^ay^b`

This implies that;

`-20x^(11)y^(7)=-20x^ay^b`

Comparing exponents, we have

a=11,b=7

The first choice is correct.

Answer 2

a=11,b=7

Explanation:

To get to the result we firs multiply the figures on the left hand side.

multiplication of each term with its similar term is shown:

5×-4=-20

x⁷ₓx⁴=x¹¹. Here we add the powers because we are multiplying indices to the same base.

y²ₓ y⁵= y⁷

Thus the correct answer is a=11 and b=7