1.1 by 1.2 by 13 by 14 by 15 (simple calculation) Off form calculation (simple calculation)

1.1 by 1.2 by 13 by 14 by 15 (simple calculation) Off form calculation (simple calculation)

This is simple. Let me teach you
1.1 times 1.2 times 13 times 14 times 15 = 0.01 * 11 * 12 * 13 * 14 * 15
=0.01*（13-2)*(13-1)*13*(13+1)*(13+2)
=0.01*13*(169-1)(169-4)
=0.13*168*165
=1.3*84*33=1.3*12*7*11*3=11*13*7*3.6
=143*7*3.6
=1001*3.6
=3 603.6
I can't do anything about the following. I can only do it in writing
The final result is 3 603.6
Do you understand the above? The main test is the square difference formula!

The parabolic equation y = - 0.5x * 2 + m, points a and B and P (2,4) are on the parabola, and the inclination angles of the lines PA and Pb are complementary. It is proved that the slope of the line AB is fixed

P (2,4) is on the parabola, which is carried into y = - 0.5x ^ 2 + m, M = 6,
Parabolic equation y = - 0.5x ^ 2 + 6
Suppose the inclination angle A1 of the straight line PA and the slope K1 = tga1;
The slope of line PA is K2 = tga2 = TG (180-a1) = - tga1 = - K1
Suppose a (x1, - 0.5x1 ^ 2 + 6), B (X2, - 0.5x2 ^ 2 + 6); P (2,4)
And K2 = - K1
(-0.5x1^2+6-4)/(x1-2)=-(-0.5x2^2+6-4)/(x2-2)
After simplification, X1 + x2 = - 4
Slope of line AB:
k=〔(-0.5x2^2+6)-(-0.5x1^2+6)〕/(x2-x1)
=-0.5(x1+x2)
=-0.5×(-4)
=2
Get proof

How much is one eighth minus one half minus one third?

One third

The quadratic function y equals 2x square minus 4x minus 6 is transformed into y equals a (X-H) square by using the collocation method

y=2(x-1)^2 -4

Add brackets to the following formula to make the equation hold. 9 × 0.6 + 4.8 △ 0.4 ― 0.3 = 486

9*(0.6+4.8)\(0.4-0.3)=486

The minimum value of the formula | x + 5 | is () which means that the value of X is ()

The minimum value of the formula | x + 5 | is (0), which means that the value of X is (- 5)

(6.4 times 5 times 8.1) divided by (3.2 times 2.5 times 2.7)
Simple calculation with computer

(6.4*5*8.1)/(3.2*2.5*2.7)
=(3.2*2*2.5*2*2.7*3)/(3.2*2.5*2.7)
=2*2*3
=12

How do polynomials and polynomials multiply

For example: (4a + 5b) x (2n + 4m)
=4a x 2n+4a x 4n+5b x 2n+5b x 4m
=8an+16am+10nb+20bm

To prepare 1000 grams of 80% alcohol into 60% alcohol, a student added 300 grams of water without consideration
Try to explain whether the student added too much water through calculation?
If the water is excessive, how many grams of 95% alcohol should be added? If the water is insufficient, how many grams of 20% alcohol should be added?

1000*80%/(1000+300)=61.5%
So the water is not too much. Not enough
Water shortage, add 20% alcohol x G
There are
(1000*80%+x*20%)/(1000+300+x)=60%
The solution is x = 50
So you need to add 50 grams

6 out of 7, 9 out of 21, 9 out of 6

6 out of 7 = 36 out of 42
9 out of 21 = 18 out of 42
9 out of 6 = 63 out of 42