Question 2: Mathematical solution of the equation (to be tested) Solution: from ②: y=-2x.
Substitute ①: x2-x? (-2x) - 2？ (-2x)2=0
x2 + 2x2 - 8x2=0
-5x2=0, then x=0.
Put X back to ②: y =-2x =-2? 0=0
It is verified that x=0 and y=0 are the solutions of the original equation.
Question 3: Mathematics. Solve equations. * To be tested, 3x=24
x=8
28-x= 12
28- 12=x
x= 16
5x=60
x= 12
Left =5* 12=60= right
x÷2.5=4
x= 10
13÷x=0.4
0.4x= 13
x=32.5
27-x= 12
27- 12=x
x= 15
Left =27- 15= 12= right
Question 4: Find the solution of mathematics (equation to be measured) 1( 1): the square of both sides;
2x + 3=x2
x2 - 2x - 3=0
(x-3)(x+ 1)=0
X = 3 or x=- 1
Test: Substitute x=3 into the original equation:
Left =√2? 3+3=√6+3=√9=3
Right =-3
∴ Left ≠ Right, then x=3 is an additional root, and it is discarded.
Substitute x=- 1 into the original equation.
Left =√2? (- 1)+3=√-2+3=√ 1= 1
Right =-(- 1)= 1= left
X =- 1 is the solution of the original equation.