Question

Zadanie w załączniku daję naj

i jeszcze to :
x-y=21
4x+5y=3


2x+y=1
x-y=5

Answer 1

A=1,5m=150cm
b=140cm
a-5cm=150-5=145cm
b-5cm=140-5=135cm
P=a*b=145cm*135cm=19575cm²=195,75m²

x-y=21
4x+5y=3
x=21+y
4(21+y)+5y=3
x=21+y
84+4y+5y=3
x=21+y
9y=3-84
x=21+y
9y=-81/:9
x=21+y
y=-9
x=12

2x+y=1
x-y=5
y=1-2x
x-(1-2x)=5
y=1-2x
x-1+2x=5
y=1-2x
3x=6/:3
y=1-2x
x=2
y=1-2*2
y=-3

Answer 2

1.
x-y=21/*5
4x+5y=3

5x-5y=105
4x+5y=3
----------------
5x-5y+4x+5y=108
x-y=21

9x=108/:9
x-y=21

x=12
12-y=21/-12

x=12
-y=9/:(-1)

x=12
y=-9

2.
2x+y=1
x-y=5
----------
2x+y+x-y=6
x-y=5

3x=6/:3
x-y=5

x=2
2-y=5/-2

x=2
-y=3/:(-1)

x=2
y=-3