Question

3х+у=7 ;9х-4у=-7,решите систему уравнений

Answer 1

Как-то так, ответ: x=1  y=4

Answer 2

3x+y=7   <=>  y=7-3x
9x-4y=-7          9x-4×(7-3х)= -7
                        9х-28-12х=-7
                        9х-12х=-7+28
                       -3х=21
                         х=21÷(-3)
                         х=-9
                                        3×(-9)+у=7
                                         -27+y=7
                                           y=7+27
                                           у=34            Ответ (-9:34)

Answer 3

To solve this system of equations, we can use the method of elimination, also known as the method of addition or subtraction. The goal is to eliminate one of the variables by adding or subtracting the two equations, and then solve for the remaining variable.

We can start by multiplying the first equation by 4 to get:

12x + 4y = 28

Now we can add this equation to the second equation to eliminate y:

12x + 4y + 9x - 4y = 28 - 7

Simplifying this gives us:

21x = 21

Dividing both sides by 21 gives us:

x = 1

Now we can substitute this value of x into one of the original equations, say the first one, to solve for y:

3x + y = 7

3(1) + y = 7

y = 4

Therefore, the solution to the system of equations is x = 1 and y = 4.