Persamaan kuadrat 2x^2+x+5=0 mempunyai akar x1 dan x2. Nilai x1^2+x2^2=…

X1^2+x2^2=(x1+x2)^2-2x1x2
X1+x2=-b/a=-1/2
X1x2=5/2
X1^2+x2^2=(x1+x2)^2-2x1x2=(-1/2)^2-2x(5/2)=1/4-5=-4 3/4
 

jika x1 dan x2 adalah akar-akar dari persamaan ax² + bx + c = 0, maka berlaku
x1 + x2 = -b/a
x1 . x2 = c/a
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2x² + x + 5 = 0, maka
x1 + x2 = -1/2
x1 . x2 = 5/2

x1² + x2² = (x1 + x2)² - 2 x1 . x2
x1² + x2² = (-1/2)² - 2 (5/2)
x1² + x2² = 1/4 - 5
x1² + x2² = 1/4 - 20/4
x1² + x2² = -19/4