Question

Rob and Lila try to simplify 18 x 4² + (9 - 3)². Rob simplifies the expression and gets 360. Lila simplifies it and gets 324. Which student is correct? What error did the other student make?

Answer 1

Lila is correct. Rob is wrong because he multiplied 18*4^2 and he gets 288 and then he added 81 and subtracted 9 and that gave him 360.

Answer 2

Lila is correct and Rob is incorrect because she apply wrong property.

`18 * 4^2+(9-3)^2=324`

Explanation:

Given : Rob and Lila try to simplify
`18 * 4^2+(9-3)^2`

Rob simplifies the expression and gets 360. Lila simplifies it and gets 324.

To find : which student is correct and what error did the other student.

Solution: First we simplify the expression:

`18 * 4^2+(9-3)^2`

`=18 * 16+(6)^2`

`=288+36`

`=324`

The solution of the expression is 324 which means Lila simplifies correct.

The mistake is found in Rob,

She simplify
`(9-3)^2` like
`9^2-3^2=81-9=72` and she put this in equation

`18 * 4^2+(9-3)^2`

`=18 * 16+9^2-3^2`

`=288+72`

`=360` which is totally in correct.

because
`(a+b)^2=a^2+b^2+2ab` she use wrong property.