Factorization a square B + AB square + a square C + AC square + b square C + BC square + 3ABC

Factorization a square B + AB square + a square C + AC square + b square C + BC square + 3ABC

a²b+ab²+a²c+ac²+b²c+bc²+3abc=(a²b+ab²+abc)+(a²c+ac²+abc)+(b²c+bc²+abc)=ab(a+b+c)+ac(a+b+c)+bc(a+b+c)=(ab+ac+bc)(a+b+c)

Factorize A's square + B's Square = 1, B's square + C's Square = 2, C's square + A's Square = 2, find AB + BC + AC's Square

A's square + B's square + B's square + C's square + C's square + A's Square = 2 times (A's square + B's square + C's Square) = 5, so a's square + B's square + C's Square = 5 / 2, in 5 / 2-B's square + C's Square = 1 / 2, i.e. a's Square = 1 / 2, we solve a, then we solve BC, and then we substitute BC into the original formula

As shown in the figure, △ ABC, ab = AC, BD is the center line on the side of AC. if the perimeter of △ abd is 3cm longer than that of △ BCD, and the perimeter of △ ABC is 21cm, then BC =?

If the perimeter of △ abd is 3 cm larger than that of △ BCD, that is, ab-bc = 3, let BC = x, then AB = x + 3, AC = x + 3
X+X+3+X+3=21
X=5
BC=5cm

How many square decimeters is 2.6 square decimeters equal to? How many square centimeters? Give me extra points in one minute!

260

The area of a trapezoid is 8.1 square decimeters, the height is 9 cm, and the length of the upper bottom is 80 cm

This problem can be solved according to the trapezoid formula, trapezoid area = (upper bottom + lower bottom) × height △ 2
1. It can be seen from the formula: upper bottom + lower bottom = area of trapezoid × 2 △ height
That is: upper bottom + lower bottom = 810 × 2 ÷ 9 (to be converted into units, 8.1 decimeters and 178; = 810cm and 178;)
Upper bottom + lower bottom = 1620 △ 9
Upper bottom + lower bottom = 180cm
2. Bottom = 180-80 = 100 cm
I don't know if you can use the equation to solve it. If you can, set the bottom of trapezoid as X, and then make the equation according to the area formula. It's easier to understand

As shown in the figure, in the triangle ABC, O is the intersection of the axis of symmetry of line AB and the axis of symmetry of line AC, and the proof angle BOC = 2 angle BAC
seek

O is the outer center of the triangle ABC
Connect OA, ob, OC
OB=OC=OA
Angle OBC = angle OCB
Angle OAB = angle abo
Angle OAC = angle ACO
Angle OBC = angle ABC - angle abo
Angle OCB = angle ACB - angle ACO
Angle BOC = 180 - angle OBC - angle OCB
=180 angle ABC + angle ABO - angle ACB + angle ACO
=(180 angle ABC angle ACB) + (angle ABO + angle ACO)
=Angle BAC + (angle OAB + angle OAC)
=Angle BAC + angle bac
=2-point bac

Given that real numbers a and B satisfy 7a = A & # 178; + 2, 7b = B & # 178; + 2, find the value of B / A + A / b

7a=a²＋2,7b=b²＋2
∴a²-7a+2=0,b²-7b+2=0
A and B are two parts of the equation x & # 178; - 7x + 2 = 0
∴a+b=7,ab=2
∴b／a+a／b
=(b²+a²)/ab
=[(a+b)²-2ab]/(ab)
=(7²-4)/2
=22.5

In Tagore's poem, if you miss the sun and shed tears, you will also miss the moon and stars

If you shed tears when you miss the sun,you also miss the stars.
I recited the bird collection

What are the similarities and differences among all kinds of trees?

Similarities: they all have roots, stems and leaves. They all need sunshine, water and soil
Differences: the size of the crown is different, the thickness of the trunk is different, and the shape of the leaves is different

When x is equal to what value, the value of - 3x + 2 is positive

The value of - 3x + 2 is positive
That is - 3x + 2 > 0, X