Question

Which properties justify the steps taken to solve the system? {2a+7b=03a−5b=31 10a+35b=0; 21a−35b=217 ​31a = 217 a = 7 2(7)+7b=0 14 + 7b = 0 7b=−14 b=−2 what are each of the steps taken?

Answer 1

9514 1404 393

Explanation:

2a+7b=0 . . . . . . . . given [eq1]

3a−5b=31 . . . . . . . .given [eq2]

10a+35b=0 . . . . . . multiplication property of equality 5×[eq1] = [eq3]

21a−35b=217 ​. . . . .multiplication property of equality 7×[eq2] = [eq4]

31a = 217 . . . . . . . . addition/substitution properties of equality [eq3]+[eq4]

a = 7 . . . . . . . . . . . . division property of equality (÷31)

2(7)+7b=0 . . . . . . . .substitution property of equality; a=7 in [eq1]

14 + 7b = 0 . . . . . . . properties of real numbers

7b=−14 . . . . . . . . . . addition property of equality; add -14

b=−2 . . . . . . . . . . . . division property of equality (÷7)