回 (7) (a-2)
= A²-A + ==
(4) (3x+5y) (3x-5y)
9x²-25y²
(7) (a+3)(a-3)
[(a+b)(a-b) の展開] 次の式を展開しなさい。
(1) (a+9)(a−9)
=a²_81
>
az-á
[おきかえによる展開]
回(1)(x-y-2)(x-y-6)
X-Y = X
(x-2)(x-6)
= x² + 8x + 12
=(x-1)²_8(x-12 +₂12
(3) (3x-2y+5) ²
=
(5) (a+2b-c)(a-2b+c)
= { a + (2h-c₁}{a- (2h-C)}
2h-Cをxとすると
= (a + x) (a- x)
8=a²-x²
=a²- (²h-C) ²
= A²-(4h² - 4hc + (²)
6)
9x²-x+36
1
(2) (20+a) (a-20)
= a² - 400
(5) (6a-7b)(7b+6a)
= 360²-496²
(8) (3) (+3)
4-9
次の式を展開しなさい。
=x²-2xy + y² 8x+8y + 12
a²-4h² +4hc-(²
(9) (3x + ²)
4x² + xy + y²
(3) (x+1.1) (x-1.
= x²_1₁21
(6) (-4a-96) (4
= -16 a² + 81 6²
(9)(x-4) (²
3
4 x ² TO
(2) (2x²-x-4) (2x²-x+3)
(2x²x)= X
(x-4) (X+3)
(2x²-x) - 12
(4) (x²-2x-1) ²
(6) (x²-2x+2)(x²+2x+2)
= (x²-x) (x²++ X).
=x²-x²
= x² - (2x + 2)²
= x4 − ( 4x² + 8x +4)
= x² - 4x² - 8x - 4
16
