<span>225^2 =50625</span>
<span>113^2=12769
</span>50625-12769=37856
379856:2=3145
B₄=54 q=3 S₄=?
b₄=b₁+3q
b₁+3*3=54
b₁=45
S₄=(b₁+b₄)*n/2=(45+54)*4/2=198
Ответ: S₄=198.
4а(а-2)-(а-4)^=
4а^-8а-(а^-8а+16)=
4а^-8а-а^+8а-16=3а^-16
-x²+4x-x+4=4x²-11x
-5x²+14x+4=0
D=14²-4×(-5)×4=196+80=276
√D=√276
x1,2=-14±√276/-2
4x^2 - 4x+1 = x-1/2
<span>4x^2 - 4x+1 -x+1/2 = 0
</span><span>4x^2 - 5x+1.5 = 0
</span>D = 25 - 4*4*1.5 = 1
x1 = (5-1) /8 = 1/2
x2 = (5+1) / 8 = 6/8 = 3/4
или
<span>4x^2 - 5x+1.5 = 0
</span><span>4x^2 - 2x-3х+1.5 = 0
</span>2х(2x-1) -1.5(2x-1) = 0
(2x-1) (2x-1.5) = 0
тогда либо 2х-1 = 0
либо 2х-1,5 = 0
х = 1/2
или х= 3/4