Practicing Success
Evaluate the product (5\(\vec{a}\) - 2\(\vec{b}\)). (3\(\vec{a}\) + 4\(\vec{b}\) ). |
15 |\(\vec{a}\)|2 + 14\(\vec{a}\).\(\vec{b}\) +8 |\(\vec{a}\)|2 -15 |\(\vec{a}\)|2 + 14\(\vec{a}\).\(\vec{b}\) -8 |\(\vec{a}\)|2 15 |\(\vec{a}\)|2 + 14\(\vec{a}\).\(\vec{b}\) -8 |\(\vec{b}\)|2 15 |\(\vec{a}\)|2 -14\(\vec{a}\).\(\vec{b}\) -8 |\(\vec{a}\)|2 |
15 |\(\vec{a}\)|2 + 14\(\vec{a}\).\(\vec{b}\) -8 |\(\vec{b}\)|2 |
We have (5\(\vec{a}\) - 2\(\vec{b}\)). (3\(\vec{a}\) + 4\(\vec{b}\) ).= (5\(\vec{a}\).3\(\vec{a}\) ) + (5\(\vec{a}\).4\(\vec{b}\) ) - (2\(\vec{b}\) .3\(\vec{a}\) ) -(2\(\vec{b}\) .4\(\vec{b}\) ) = 15\(\vec{a}\).\(\vec{a}\) + 20\(\vec{a}\).\(\vec{b}\) - 6\(\vec{a}\).\(\vec{b}\) - 8\(\vec{b}\).\(\vec{b}\) = 15 |\(\vec{a}\)|2 + 14\(\vec{a}\).\(\vec{b}\)-8 |\(\vec{a}\)|2
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