If a + B = 7cm and A-B = 3cm, find the difference of their surface areas

If a + B = 7cm and A-B = 3cm, find the difference of their surface areas

Solution 1
The difference of surface area is
6a^2-6b^2
=6*(a^2-b^2)
=6*(a+b)*(a-b)
=6*7*3
=126 square centimeters
Solution 2
From a + B = 7
a-b=3
The solution is a = 5, B = 2
So the difference in area is
6a^2-6b^2
=6*5*5-6*2*2
=126 square centimeters

If the length and width of the rectangular wood block are cut off by xcm, the area of the processed wood block is equal to that of the original one
If the length and width of the rectangular wood block are cut off by xcm, the functional relationship between the area YCM & sup2; and xcm is
A.y=ab-x²
B.y=x²-(a+b)x+ab
C.y=x²+(a+b)x-ab
D. None of the above answers is correct
2. Given the quadratic function y = x & sup2; - BX + 1 (- 1 ≤ B ≤ 1), when B changes gradually from - 1 to 1, its corresponding parabola position also changes
A. First move to the top left, then move to the bottom left
B. First move to the lower left, then move to the upper left
C. First move to the top right, then move to the bottom right
D. First move to the bottom right, then move to the top right
Can you tell me why

If the length and width of the rectangular wood block are cut off by xcm, the functional relationship between the area YCM & sup2; and xcm is
A.y=ab-x²
B.y=x²-(a+b)x+ab
C.y=x²+(a+b)x-ab
D. None of the above answers is correct
Y = (A-X) * (b-X) so D is correct
2. Given the quadratic function y = x & sup2; - BX + 1 (- 1 ≤ B ≤ 1), when B changes gradually from - 1 to 1, its corresponding parabola position also changes
A. First move to the top left, then move to the bottom left
B. First move to the lower left, then move to the upper left
C. First move to the top right, then move to the bottom right
D. First move to the bottom right, then move to the top right
Y = (X-B / 2) * (X-B / 2) + 1-B * B / 4, so D is correct

A cuboid is ACM in length, BCM in width and HCM in height. If the length and width remain unchanged, the height of adadsad increases by 7cm, and the volume increases ()

-- that's a simple question```
You just need to count it in
Suppose a = 1, B = 2, H = 3
1X2X（3+7）-1X2X3
=20-6
=14
=7（1X2）
=7AB