Question

A student says that if 5x2 = 20, then x must be equal to 2. Do you agree or disagree with the student? Justify your answer.

Answer 1

Answer:

Yes I agree because

what have they given,

5x2 =20

5×2=10 okay

10x=20

if 10 goes to other side of is equal to symbol, then

x=2

Answer 2

Not agree. Because, x can be +2 or -2.

Step-by-step explanation:

No, i am not agree with him. Because, the square root may be negative as well as positive.

If it would be negative, answer will be same.

So it claims that it must be positive, is wrong.

• Now, $5x^2 = 20$

$x^2 = \dfrac{20}{5}$

$x^2 = 4$

$x = \pm2$

x = +2, -2

• Now, $5(+2)^2 = 5 \times 4 = 20$

$5(-2)^2 = 5 \times 4 = 20$

Thus, it is wrong to claim that x must be 2.

x can be +2 or -2.