Question

Hey can anyone help plz?

Which expression is equal to 2√28-5√63?
A.) √7
B.) -37√7
C.) -11√7
D.) -√7

Answer 1

We have been given an expression
`2√(28) -5√(63)` and we are asked to find correct option from the given choices.

Let us simplify our expression.

`2√(28) -5√(63)`

First of all we will take out perfect squares from our radical.

`2√(7\cdot4) -5√(7\cdot9)`

`2√(4) \cdot√(7) -5√(9) \cdot√(7)`

`2\cdot2√(7) -5\cdot3√(7)`

`4√(7) -15√(7)`

`-11√(7)`

Our expression simplifies to
`-11√(7)`, therefore, option C is the correct choice.