Question

Daniel incorrectly solved the equations shown. Explain what he did wrong in each situation and then solve both equations correctly. 16x2 - 9 = 16

V16x2 - 19 - + 16
4x - 3 - +4
4x = +7
* = 14
(a)
IN
y3 - 1 = 7
= 8
(b)
y = 2

Answer 1

Explanation:

the scanned description is very hard to understand.

so I think what happened :

16x² - 9 = 16

then the first error :

sqrt(16x²) - sqrt(9) = sqrt(16)

that is wrong, as you cannot split a + or - operation inside a sqrt function into + or - separate sqrt results of the parts.

so, correctly, the only possible transformation involving sqrt for both sides :

sqrt(16x² - 9) = sqrt(16)

but it would be even easier to clean up the various constant numbers with each other.

so,

16x² - 9 = 16

16x² = 25

and now we trashes the square root

sqrt(16x²) = sqrt(25)

4x = 5

x = 5/4 or x = -5/4

and I cannot see or understand for my life what the second equation was, as Daniel did something wrong, so I cannot deduct the original equation out of a supposedly wrong

y³ - 1 = 7