16a+4b=20, -33a+8b=-47

Question

solve by elimination 16a+4b=20, -33a+8b=-47.

Answer 1

Elimination method:

The system of equations are 16a + 4b = 20  ------------> (1)

                                     - 33a + 8b = - 47 -----------> (2)

Multilply equation (1) by 2, then write the two equations in column form, then subtract one from another.

32a + 8b = 40

- 33a + 8b = - 47

( - )_______________

65a = 87

a = 87/65.

Substitute a = 87/65 in equation (1).

16(87/65) + 4b = 20

4b = 20 - (1392/65)

4b = (20*65 - 1392) / 65

4b = (1300 - 1392) / 65

4b = - 92 / 65

b = - 92/(65*4)

b = - 23/65.

The solution of the given system is a = 87/65 and b = - 23/65.