Question

HELPPPP

which value is equal to 2✓28-5✓63?

a-37✓7
b-✓7
c-11✓7
d✓7​

Answer 1

c

Explanation:

if I understand this right, then the expression is

2×sqrt(28) - 5×sqrt(63)

let's look for squared factors in the numbers under the square roots.

28 = 4×7 (4 is a squared number)

63 = 9×7 (9 is a squared number)

so,

2×sqrt(4×7) - 5×sqrt(9×7) =

= 2×2×sqrt(7) - 5×3×sqrt(7) = 4×sqrt(7) - 15×sqrt(7) =

= (4 - 15)×sqrt(7) = -11×sqrt(7)