algebra question

Question

40=c^2 Can you find the answer for c

Answer 1

If this problem said c² = 4 what would you say the answer is? Obviously the answer is 2 because 2•2 = 4. But what about -2? (-2)•(-2) = 4 as well so both +2 and -2 are "square roots" of 4. To do this problem mathematically we start with:

c² = 4 then take the square root of both sides:

√c² = √4 The square root of c² is just c (because c•c = c²) and the square root of 4 is ±2 so:

c = ±2 (either plus 2 or -2)

In your problem, it is the same, just a different number:

c² = 40

√c² = ±√40

But 40 doesn't have a nice even square root. It can be factored though into 4•10 and so we can simplify it a little because we CAN take the square root of 4:

c = ±√40

c = ±√(4•10)

c = ±2√10

Answer 2

c² = 40

Take the square root on both sides to get "c" by itself.

c = ±√40

c = ±√(4)(10)

c = ± 2√10