Question

Roopa and Noor try to simplify the expression 18 x 4 the power of 2 + (9-3) the power of 2. Roopa simplifies the expression and gets 360. Noor simplifies the expression and gets 324. Which student is correct? What error did the other student make?

Answer 1

Noor was correct while roopa was wrong. Roopa mistakenly squared both the value of 9 and 3 before taking the difference instead of subtracting 3 from 9 first and then squaring the result according to Noor.

Explanation:

Noor simplifies the expression as thus;

Looking at the expression,

18×4²+(9-3)²

Using BODMAS, we will solve the one in the bracket first to have;

= 18×4² +6²

Afterward, we simplify the product (multiplication)

(18×4²)+6²

= 288+6²

= 288+36

Then finally we will add to have 324.

This gives the correct answer because the BODMAS rule was followed.

Roopa mistakenly simplify the expression as thus by squaring both values of 9 and 3 to give;

18×4²+(9²-3²)

18×4²+(81-9)

= 18×4²+(72)

= 288+72

= 360

Answer 2

Noor was right because the answer is 324

Explanation:

the BODMA rule of solving the expression the bracket first before applying the index or before multiplying.

The correct way of solving the expression is

18 x 4x 4 + (9-3)(9-3)

= 18×16 + 6×6

= 288 + 36

= 324

But

Roopa solved it this way instead

18 x 4x 4 + (9×9-3×3)

= 18×16 + (81-9)

= 288 + 72

= 360

So, Noor was right while Roopa was wrong