Solve the equation process 1 x squared 3 x 40 0 2 x 1 x 4 12 5

1.Multiply with crosses

x`2+3x-40=0

x+8)(x-5)=0

x=—8 or x=5

2.Let's take it apart first

x`2+3x-4=12

x`2+3x-16=0

Then use the formula method, x=[ -b (b 2-4ac) ]2a) in this formula, a=1, b=3, c= - 16 (note the negative sign), x=(-3 73) 2

The upstairs one that solved x=2 and x=-8 was wrong, and it didn't work to bring it in.

x2+3x+9=25

x+3) 2=25 here(x+3) 2=x 2+6x+9 instead of x 2+3x+9

The equation can be varied into (x+1)(x 3+1)+x 2=0(x+1) and (x 3+1) with plus or minus signs, and when x=0, x 4+x 3+x 2+x+1=1>0, Soling Fangshi has no real roots in this equation, and there are four imaginary collapses: 5 (1 2) 4 + 2 (1 2)*(5 (1 2) +5) (1 2)*i) 4 - 1 45 (1 2) 4 - 2 (1 2)*(5 (1 2) +

Prepare x+30=(Imitation or no 1+.)

Solution: Group Elder. x=50

The first step is to determine the relationship between =b 2-4ac and 0, if b 2-4ac 0 then there are two unequal real roots, and if b 2-4ac 0 then there are two equal real roots.

If b 2-4ac 0

Then there is no solution.

If there is a solution, x=[-b (b 2-4ac)] 2a) I'll solve it now.

Solution: b 2-4ac=(-1) 2-4*(1 3)*(0x=[-b (b 2-4ac)] 2a)=[1 (5 3)] 2 3).

x1=3/2+√15/2

x2=3/2-√15/2

Solution: x +3x-40=0, decomposed by cross multiplication (x+8)(x-5)=0

x+8=0 or x-5=0

x1=-8, x2=5

x-1)(x+4)=12

x²+4x-x-4=12

x +3x=16, with matching method.

x²+3x+(3/2)²=16+(3/2)²(x+3/2)²=73/4

x+3/2=±√(73/4)

x+3/2=±√73/2

x1=(-3+√73)/2

x2=(-3-√73)/2

（3+5x/2-1=4x/3-1/3;

5x/2-4x/3=-1/3-2;

7x/6=-7/3;

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a*a-2ab+b*b=(a-b)*(a-b);

x*solution: (root number on both sides: or.)

i.e. x=5 or.

I hope it helps you, I don't know how to ask.