Question

Choosing Correct Student Work
Three students simplify the expression 2z(1.4z – 4.3). Which student’s work is correct?

2 z (1.4 z minus 4.3). (2 z)(1.4 z) + (2 z)(negative 4.3). 2.8 z squared minus 8.6 z

2 z (1.4 z minus 4.30. (2 z)(1.4 z) + (2 z)(4.3). 2.8 z squared + 8.6 z

2 z (1.4 z minus 4.3). (2 z)(1.4 z) minus (4.3). 2.8 z squared minus 4.3

Answer 1

Student 1 is correct.

Distribute 2z to both terms: (2z)(1.4z) + (2z)(−4.3) = 2.8z^2 − 8.6z.

Student 2 got the sign wrong (should be −8.6z), and Student 3 failed to multiply the −4.3 by 2z.