Question

Solve the simultaneous equation

(use substitution please!)

3x-2y=21
4x+3y=11

x= ?
y= ?​

Answer 1

`3x -2y =21 ~~....(i)\\\\4x+3y = 11~~~...(ii)\\\\\text{From (i)}\\\\3x - 2y = 21 \\\\\implies x = \frac{21+2y}3 = 7 +\frac{2y}3 ~~~...(iii).\\\\\text{Substitute x in equation (ii):}\\\\4\left( 7 + \frac{2y}3 \right) + 3y = 11\\\\\\\implies 28 + \frac{8y}3 + 3y =11\\\\\implies \frac{17y}3 = 11-28 = -17\\\\\implies \frac{y}3 = -1\\\\\implies y =-3\\\\\text{Substitute} ~ y =-3 ~ \text{in equation (iii):}\\\\\x=7+\frac{2(-3) }3 = 7-2 =5\\\\\text{Hence,} ~(x,y) = (5,-3)`