X^3 - 21x = -20
add 20 to both sides
x^3 - 21 x + 20 = 0
Rational Root Theorem:
Factors of P (constant) 20 = 1, 2, 4, 5, 10, 20
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Factors of Q (leading Coefficient) = 1
Possible zeros (all + -) 1/1, 2/1, 4/1, 5/1, 10/1, 20/1
Of the choices given only the number 1 is a possible root.
From top to bottom :
D, E, A, C
I think that is right and I hope it helps!
<span><span>2<span>(<span>1+<span>5x</span></span>)</span></span>=<span>5<span>(<span><span>2x</span>−1</span>)</span></span></span>
Step 1: Simplify both sides of the equation.<span><span>2<span>(<span>1+<span>5x</span></span>)</span></span>=<span>5<span>(<span><span>2x</span>−1</span>)</span></span></span><span><span><span><span>(2)</span><span>(1)</span></span>+<span><span>(2)</span><span>(<span>5x</span>)</span></span></span>=<span><span><span>(5)</span><span>(<span>2x</span>)</span></span>+<span><span>(5)</span><span>(<span>−1</span>)</span></span></span></span>(Distribute)<span><span>2+<span>10x</span></span>=<span><span><span>10x</span>+</span>−5</span></span><span><span><span>10x</span>+2</span>=<span><span>10x</span>−5</span></span>
Step 2: Subtract 10x from both sides.<span><span><span><span>10x</span>+2</span>−<span>10x</span></span>=<span><span><span>10x</span>−5</span>−<span>10x</span></span></span><span>2=<span>−5</span></span>
Step 3: Subtract 2 from both sides.<span><span>2−2</span>=<span><span>−5</span>−2</span></span><span>0=<span>−7</span></span><span>
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The third one is the answer for this question