On the equation of X (M + 1) the square of X + (1 + 2x) M = 2 when m is a value, the equation has two unequal real roots and the equation has two equal real roots

On the equation of X (M + 1) the square of X + (1 + 2x) M = 2 when m is a value, the equation has two unequal real roots and the equation has two equal real roots

1、
(m+1)x²+2mx+m-2=0
There are two unequal real roots
The discriminant is greater than 0
4m²-4(m+1)(m-2)>0
m²-m²+m+2>0
m>-2
And the coefficient of X & sup2; is not equal to 0
therefore
m> And m ≠ - 1
2、
There are two equal real roots
The discriminant is equal to 0
4m²-4(m+1)(m-2)=0
m=-2

When Xiaoli buys some clothes for the school chorus, the store manager gives the following preferential terms: if the one-time purchase is no more than 10 pieces, the unit price is 80 yuan; if the one-time purchase is more than 10 pieces, the unit price of all the clothes purchased will be reduced by 2 yuan for each additional piece, but the unit price should not be less than 50 yuan. According to this preferential terms, Xiaoli pays 1200 yuan for one-time purchase of this kind of clothes How many of these clothes did she buy?

Let's buy x pieces of this kind of clothes. According to the meaning of the question, we can get that [80-2 (X-10)] x = 1200, the solution is: X1 = 20, X2 = 30, when x = 30, 80-2 (30-10) = 40 (yuan) < 50 does not fit the question. A: she bought 20 pieces of this kind of clothes

2X square - 4 √ 2x + 3 = 0
2X square - 4 √ 2x + 3 = 0
The square of 2x - 4 root sign 2x + 3 = 0

2X & sup2-4 √ 2x + 3 = 0 2x & sup2-4 √ 2x + 3 = 0 2x & sup2-4 √ 2x = - 3x & sup2-2 √ 2x = - 3 / 2x & sup2-2 √ 2x + (√ 2) & sup2 = - 3 / 2 + (√ 2) & sup2 (x - √ 2) & sup2 = - 3 / 2 + 2 (x - √ 2) & sup2 = 1 / 2x - √ 2 = ± (√ 2) / 2, so we get two roots: X & # 8321 = (3 √ 2) / 2x & # 8322 =