Write each of the following as an equation in two variables:
(i) x = – 5 (ii) y = 2
(iii) 2x = 3 (iv) 5y = 2.
Which one of the following options is true, and why?
y = 3x + 5 has
(i) a unique solution,
(ii) only two solutions,
(iii) infinitely many solutions.
2x +y = 7
2x + y = 7
⇒ y = 7 – 2x
Put x = 0, we get y = 7 – 2(0) = 7 – 0 = 7
Put x = 1, we gety = 7 – 2(1) = 7 – 2 = 5
Put x = 2, we get y = 7 — 2(2) = 7 – 4 = 3
Put x = 3, we get y = 7 – 2(3) = 7– 6 = 1
∴ Four solutions are (0, 7), (1, 5), (2, 3) and (3, 1).