Question

Multiply: (x + 3y) by (3x - 4y).​

Answer 1

Step-by-step explanation:

$(x + 3y)(3x - 4y) \\ 3 {x}^{2} - 4xy + 9xy - 12 {y}^{2} \\ 3 {x}^{2} + 5xy - 12 {y}^{2}$

Answer 2

Step-by-step explanation:

x+3y=11 *3 (1 equation)

3x-4y=7 *1 (2 equation)

3x+9y=33 (We will Subtract these 2 equations)

3x-4y=7

- + -

13y= 26

y= 26/13

y=2

putting y in equation 1

x+3y=1

x+3(2)=1

x+6=1

x=1-6

x= -5