When the factorization method is used to solve the equation x & # 178; - BX + C = 0, the left side of the equation is decomposed to (x-3) (x + 5) = 0, then B =? C =?

When the factorization method is used to solve the equation x & # 178; - BX + C = 0, the left side of the equation is decomposed to (x-3) (x + 5) = 0, then B =? C =?

(x-3)(x+5)=x²+2x-15=0
The comparison shows that - B = 2, C = - 15
Then B = - 2, C = - 15

Solving quadratic equation x ^ 2-bx-2b ^ 2 = 0 by factorization
And ABX ^ 2 - (a ^ 2 + B ^ 2) x + AB = 0

It can be decomposed into (x-2b) (x + b) = 0
The second decomposition is (ax-b) (bx-a) = 0

The factorization shows that 36 ^ 7-6 ^ 12 can be divided by 35

Original form
=6^14-6^12
=6^12(36-1)
=6^12*35

Test your IQ application questions!
A typist typed a manuscript. On the first day, he typed 25% of the total. On the second day, he typed 40% of the total. On the second day, he typed six more pages than on the first day?

6 / (40% - 25%) = 40 (pages)

The circumference of a rectangle is 32 cm. If the length is 9 cm, the width is 7 cm. When the length of a rectangle becomes smaller, how does the width change?
Write the product of two numbers corresponding to length and width. Are these products equal? Is the length and width of a rectangle inversely proportional when the perimeter is constant? Why?

1. As the length of a rectangle decreases, its width increases
2. Length = 10 cm, width = 6 cm, product = 10 × 6 = 60 square cm
Length = 12 cm, width = 4 cm, product = 12 × 4 = 48 square cm
So: the product is not equal
3. When the circumference is constant, the length and width of a rectangle are not in inverse proportion, because the product of length and width is not a fixed value, but a variable value

Round off for approximation
4730120 = () million.57436053263 = () billion
Approximate number, what is it? Can you tell me, I don't know what it means

4730120 = (4.73) million.57436053263 = (57.4) billion
A number is close to the exact number (slightly more or less than the exact number), which is called approximate number
Rounding method is the most commonly used method to find approximate numbers. It is mainly to round off the mantissa when the mantissa omitted is 4 or more than 4 hours. If the number on the highest order of the mantissa omitted is 5 or more than 5, after the mantissa omitted is removed, it is necessary to forward one bit. For example, 3096401 ≈ 3.1 million, 1 △ 3 = 0.333 It can be seen from the above two examples that the approximate number is smaller than the accurate value when rounding, and larger than the accurate value when rounding

A railway bridge is 1000 meters long, the train is completely on the bridge for 80 seconds, and the train is 120 seconds from entering to leaving

(120-80) / 2 = 20 seconds 1000 / (80 + 20) = 10m / s 10 * 20 = 200m a: 200m long

It is known that the length of a rectangle is xcm, and the width is 3cm less than the length. Try to write out the perimeter y and length x of the rectangle, and find out the value range of the independent variable x

1. The width is (x-3), the perimeter is y = 2 * (x + x-3) = 4x-6
2. Ensure x-3 > 0, so x > 3

N + 2 power of (a + b) - N + 1 power of 2 (a + b) + n power of (a + b)

(a + b) ^ (n + 2) - 2 (a + b) ^ (n + 1) + (a + b) ^ n = (a + b) ^ n [(a + b) ^ 2-2 (a + b) + 1] = (a + b) ^ n * (a + B-1) satisfied, thank you for adopting, give a "can solve + original"!

If it's more than 3 minutes, pay 0.3 yuan for every more than 1 minute. Xiao Ming pays 2.9 yuan for a call to a certain place. How many minutes did he make a call?

3 + (2.9-0.8) △ 0.3, = 3 + 2.1 △ 0.3, = 3 + 7, = 10 (minutes); a: he called for 10 minutes