3x-2y = 1,5x + 3Z = 8,3y-6z = - 3 help to solve this cubic equation,

3x-2y = 1,5x + 3Z = 8,3y-6z = - 3 help to solve this cubic equation,

3x-2y=1,(1)
5x+3z=8,(2)
3y-6z=-3,(3)
(2)*2,
10x+6z=16(4)
(4)+(3),
10x+3y=13(5)
(1)*3+(5)*2
x=1,y=1,z=1
X=1
Y=1
Z=1
Convinced the landlord, I can see that x, y and Z are all equal to 1
X=Y=Z=1
5x + 2Y = x + 3Z; 3x + 3Y = 2Y + 2Z; X + 2Y + Z = NX; find n
N=5
We can get 4x + 2Y = 3Z; 3x + y = 2Z by shifting the terms of the first two formulas. We can get x + y = Z by subtracting the second formula from the first formula. We can get x = y by multiplying both sides of 3x + y = 2Z by 1.5 and subtracting them from 4X + 2Y = 3Z. Then the final formula is x + 2x + (x + y) = x + 2x + X + x = 5x
N cannot be solved
=5
1、5x+2y=x+3z------>2y=-4x+3z
2、3x+3y=2y+2z----->y=2z-3x
3. The solution is Z = 2x; y = X
4、x+2y+z=nx ----->n=5
5x+2y=x+3z ①
3x+3y=2y+2z ②
x+2y+z=nx ③
① - 2 - 3 = 0, we get: (2-N) x + 3Y = 0, we deduce y = (n-2) x / 3, we get the relation between X and Z by taking y into the original formula
4X + 2 * (n-2) x / 3 = 3Z; 3 (n-1) X-2 (n-2) x = 3Z; eliminate Z to get 5x-nx = 0, get n = 5
How to solve 0.3x = (210-x) * 0.4
It's a process
0.3x=(210-x)*0.4
0.3x=84-0.4x
0.3x+0.4x=84
0.7x=84
x=84/0.7
x=120
0.3x=84-0.4x
0.7x=84
x=120
Hope to help you.
3x-1>x+1 { x+8
3x-1>x+1
2x>2
X>1
x+89
X>3
So x > 3
（x-30）（162-3x）=432
（x-30）（162-3x）=432
162X-4860-3x^2+ 90X =432
-3X^2+252X-5292=0
3X^2-252X+5292=0
X^2-84X+1764=0
(X-42)=0
X=42
4x-3x ^ 2-8's best value idea! The foundation is not good
4x-3x^2-8
=-3x^2+4x-8
=-3(x-2/3)^2-20/3
When x = 2 / 3, there is a maximum of - 20 / 3
= -3x∧2+4x-8 = -3(x∧2-4/3+8/3) =-3[(x-2/（3∧0.5）) ∧2+4/3]
How to solve "3x + x = 30 + X"?
4x-x=30 3x=30 x=10
Is there something missing?
What do you mean?
Can we calculate directly, x = 10?
Find the maximum value of - 3x ^ 2 + 4x-8
=-3[x^2-2×(2/3)x+(2/3)^2]-8+(-3)(2/3)^2
Why is this process written like this?
Is it a rare recipe he uses?
I still can't understand it
Yes, it's a matching method. I'll tell you in detail. - 3x & sup2; + 4x-8 & the original formula = - 3 [x & sup2; + (4 / 3) x] - 8 & first, we will collect those with X and extract - 3 = - 3 [x & sup2; + (4 / 3) x + (2 / 3) & sup2; - (2 / 3) & sup2;] - 8 & this is an important step in the matching method. Divide the coefficient in front of X by 2 and then square it
yes.
The original formula = - 3 [x & sup2; - (4 / 3) x)] - 8
=－3[x²－2(2/3)x＋(2/3)²]－8＋ (－3)(2/3)²
↓ ↓ ↓
Remarks: [A & sup2; - 2 B a + B & sup2;] = (a-b) & sup2;
As for the addition of - 3 after the expansion
yes.
The original formula = - 3 [x & sup2; - (4 / 3) x)] - 8
=－3[x²－2(2/3)x＋(2/3)²]－8＋ (－3)(2/3)²
↓ ↓ ↓
Remarks: [A & sup2; - 2 B a + B & sup2;] = (a-b) & sup2;
As for the addition of - 3 × (2 / 3) & sup2;, it is because in the step of - 3 [x & sup2; - 2 (2 / 3) x + (2 / 3) & sup2;],
Multiplying - 3 is equivalent to subtracting (- 3) (2 / 3) & sup2; from the whole formula, so we need to add (- 3) (2 / 3) & sup2;
Can be equal to the original. Put it away
How to solve 3x + (30-x) * 2 = 70
How to solve 4x + (35x) * 3 = 120
3x+(30-x)*2=70
3x+60-2x=70
x=10
When x = what, 4x + 8 is equal to 3x-10
x=-18