In the expansion of (x + 1) 3 + (x + 1) 4 + (x + 1) 5 + (x + 1) 6 + (x + 1) 7, the coefficient of X4 is? (the following numbers are all to the power.)

In the expansion of (x + 1) 3 + (x + 1) 4 + (x + 1) 5 + (x + 1) 6 + (x + 1) 7, the coefficient of X4 is? (the following numbers are all to the power.)

The coefficient is 1 + 5 + 15 + 35 = 56
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If △ x [

△ = (1 / 10) [= (15) □ = (8)

The equation x (4x + 3) = 3x + 1 is reduced to the general form, and its quadratic coefficient is
The equation x (4x + 3) = 3x + 1 is reduced to the general form, and its quadratic coefficient is, the coefficient of the first term is, and the constant term is,

4x^2+3x=3x+1
4x^2-1=0
The quadratic coefficient is 4 and the primary coefficient is 0
The constant term is - 1
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