How to calculate the square of x plus 10x + 21 = 0

How to calculate the square of x plus 10x + 21 = 0

x^2+10x+21=0
1 3
1 7
（x+7）（x+3）=0
X = - 3 or x = - 7

Solve the following equation (1) x2-10x + 25 = 7; (2) (x-1) 2 + 2x (x-1) = 0

(1) X 2-10x + 25 = 7, transfer term: X 2-10x + 18 = 0, B 2-4ac = (- 10) 2-4 × 1 × 18 = 28, x = 10 ± 282 × 1, x 1 = 5 + 7, x 2 = 5-7. (2) (x-1) 2 + 2x (x-1) = 0, decomposition factor: (x-1) (x-1 + 2x) = 0, namely X-1 = 0, X-1 + 2x = 0, solution equation: x 1 = 1, x 2 = 13

The square of X - 10x + 25 = the square of a
Formula method

x²-10x+25-a=0
So the discriminant = 10 & sup2; - 4 (25-A) = 100-100 + 4A = 4A
So x = (10 ± 2 √ a) / 2
So x = 5 - √ a, x = 5 + √ a

-10x square + 4x + 1 = 5x + 2x square - 2. How to get 12x square + x-3 = 0? Write down the steps

The original formula: - 10x & # 178; + 4x + 1 = 5x + 2x & # 178; - 2 → move to (move the left item to the right, pay attention to the sign change) → 10x & # 178; + 2x & # 178; + 5x-4x-2-1 = 0 → 12x & # 178; + x-3 = 0, I hope it can help you